diff --git a/lib/diamond/filters.ts b/lib/diamond/filters.ts
new file mode 100644
index 00000000..facaa3c0
--- /dev/null
+++ b/lib/diamond/filters.ts
@@ -0,0 +1,73 @@
+import { FacetCutAction } from './utils';
+import { AddressZero } from '@ethersproject/constants';
+
+export interface FacetFilter {
+  type: string;
+  action: FacetCutAction;
+  contract: string;
+  selectors: string[];
+}
+
+// returns true if the selector is found in the only or except filters
+export function selectorIsFiltered(
+  only: FacetFilter[],
+  except: FacetFilter[],
+  contract: string,
+  selector: string,
+): boolean {
+  if (only.length > 0) {
+    // include selectors found in only, exclude all others
+    return includes(only, contract, selector);
+  }
+
+  if (except.length > 0) {
+    // exclude selectors found in except, include all others
+    return !includes(except, contract, selector);
+  }
+
+  // if neither only or except are used, then include all selectors
+  return true;
+}
+
+// returns true if the selector is found in the filters
+export function includes(
+  filters: FacetFilter[],
+  contract: string,
+  selector: string,
+): boolean {
+  return filters.some(
+    (filter) =>
+      [filter.contract, AddressZero].includes(contract) &&
+      filter.selectors.includes(selector),
+  );
+}
+
+// validates that different filter types do not contain the same contract
+export function validateFilters(only: FacetFilter[], except: FacetFilter[]) {
+  if (only.length > 0 && except.length > 0) {
+    only.forEach((o) => {
+      except.forEach((e) => {
+        if (o.contract === e.contract) {
+          throw new Error(
+            'only and except filters cannot contain the same contract',
+          );
+        }
+      });
+    });
+  }
+}
+
+export function destructureFilters(
+  filters: FacetFilter[],
+  action?: FacetCutAction,
+) {
+  const only = filters.filter((f) => f.type === 'only');
+  const except = filters.filter((f) => f.type === 'except');
+
+  if (action !== undefined) {
+    only.filter((f) => f.action === action);
+    except.filter((f) => f.action === action);
+  }
+
+  return { only, except };
+}
diff --git a/lib/diamond/utils.ts b/lib/diamond/utils.ts
new file mode 100644
index 00000000..284b651e
--- /dev/null
+++ b/lib/diamond/utils.ts
@@ -0,0 +1,296 @@
+import {
+  FacetFilter,
+  destructureFilters,
+  selectorIsFiltered,
+  validateFilters,
+} from './filters';
+import { AddressZero } from '@ethersproject/constants';
+import { Contract, ContractReceipt } from '@ethersproject/contracts';
+import {
+  IDiamondReadable,
+  IDiamondWritable,
+} from '@solidstate/typechain-types';
+
+export enum FacetCutAction {
+  ADD,
+  REPLACE,
+  REMOVE,
+}
+
+export interface Facet {
+  target: string;
+  selectors: string[];
+}
+
+export interface FacetCut extends Facet {
+  action: FacetCutAction;
+}
+
+// returns a list of function signatures for a contract
+export function getFunctionSignatures(contract: Contract): string[] {
+  return Object.keys(contract.interface.functions);
+}
+
+// returns a list of selectors for a contract
+export function getSelectors(contract: Contract): string[] {
+  return getFunctionSignatures(contract).map((signature) =>
+    contract.interface.getSighash(signature),
+  );
+}
+
+// returns a list of Facets for a contract
+export function getFacets(contracts: Contract[]): Facet[] {
+  return contracts.map((contract) => {
+    return {
+      target: contract.address,
+      selectors: getSelectors(contract),
+    };
+  });
+}
+
+// returns a FacetCut
+export function getFacetCut(
+  target: string,
+  selectors: string[],
+  action: number = 0,
+): FacetCut {
+  return {
+    target: target,
+    action: action,
+    selectors: selectors,
+  };
+}
+
+// returns true if the selector is found in the facets
+export function selectorExistsInFacets(
+  selector: string,
+  facets: Facet[],
+): boolean {
+  return facets.some((facet) => facet.selectors.includes(selector));
+}
+
+// preview FacetCut which adds unregistered selectors
+export async function addUnregisteredSelectors(
+  diamond: IDiamondReadable,
+  contracts: Contract[],
+  filters: FacetFilter[] = [],
+): Promise<FacetCut[]> {
+  const { only, except } = destructureFilters(filters, FacetCutAction.ADD);
+  validateFilters(only, except);
+
+  const diamondFacets: Facet[] = await diamond.facets();
+  const facets = getFacets(contracts);
+
+  let selectorsAdded = false;
+  let facetCuts: FacetCut[] = [];
+
+  // if facet selector is unregistered then it should be added to the diamond.
+  for (const facet of facets) {
+    for (const selector of facet.selectors) {
+      const target = facet.target;
+
+      if (
+        target !== diamond.address &&
+        selector.length > 0 &&
+        !selectorExistsInFacets(selector, diamondFacets) &&
+        selectorIsFiltered(only, except, target, selector)
+      ) {
+        facetCuts.push(
+          getFacetCut(facet.target, [selector], FacetCutAction.ADD),
+        );
+
+        selectorsAdded = true;
+      }
+    }
+  }
+
+  if (!selectorsAdded) {
+    throw new Error('No selectors were added to FacetCut');
+  }
+
+  return groupFacetCuts(facetCuts);
+}
+
+// preview FacetCut which replaces registered selectors with unregistered selectors
+export async function replaceRegisteredSelectors(
+  diamond: IDiamondReadable,
+  contracts: Contract[],
+  filters: FacetFilter[] = [],
+): Promise<FacetCut[]> {
+  const { only, except } = destructureFilters(filters, FacetCutAction.REPLACE);
+  validateFilters(only, except);
+
+  const diamondFacets: Facet[] = await diamond.facets();
+  const facets = getFacets(contracts);
+
+  let selectorsReplaced = false;
+  let facetCuts: FacetCut[] = [];
+
+  // if a facet selector is registered with a different target address, the target will
+  // be replaced
+  for (const facet of facets) {
+    for (const selector of facet.selectors) {
+      const target = facet.target;
+      const oldTarget = await diamond.facetAddress(selector);
+
+      if (
+        target != oldTarget &&
+        target != AddressZero &&
+        target != diamond.address &&
+        selector.length > 0 &&
+        selectorExistsInFacets(selector, diamondFacets) &&
+        selectorIsFiltered(only, except, target, selector)
+      ) {
+        facetCuts.push(getFacetCut(target, [selector], FacetCutAction.REPLACE));
+
+        selectorsReplaced = true;
+      }
+    }
+  }
+
+  if (!selectorsReplaced) {
+    throw new Error('No selectors were replaced in FacetCut');
+  }
+
+  return groupFacetCuts(facetCuts);
+}
+
+// preview FacetCut which removes registered selectors
+export async function removeRegisteredSelectors(
+  diamond: IDiamondReadable,
+  contracts: Contract[],
+  filters: FacetFilter[] = [],
+): Promise<FacetCut[]> {
+  const { only, except } = destructureFilters(filters, FacetCutAction.REMOVE);
+  validateFilters(only, except);
+
+  const diamondFacets: Facet[] = await diamond.facets();
+  const facets = getFacets(contracts);
+
+  let selectorsRemoved = false;
+  let facetCuts: FacetCut[] = [];
+
+  // if a registered selector is not found in the facets then it should be removed
+  // from the diamond
+  for (const diamondFacet of diamondFacets) {
+    for (const selector of diamondFacet.selectors) {
+      const target = diamondFacet.target;
+
+      if (
+        target != AddressZero &&
+        target != diamond.address &&
+        selector.length > 0 &&
+        !selectorExistsInFacets(selector, facets) &&
+        selectorIsFiltered(only, except, AddressZero, selector)
+      ) {
+        facetCuts.push(
+          getFacetCut(AddressZero, [selector], FacetCutAction.REMOVE),
+        );
+
+        selectorsRemoved = true;
+      }
+    }
+  }
+
+  if (!selectorsRemoved) {
+    throw new Error('No selectors were removed from FacetCut');
+  }
+
+  return groupFacetCuts(facetCuts);
+}
+
+// preview a FacetCut which adds, replaces, or removes selectors, as needed
+export async function previewFacetCut(
+  diamond: IDiamondReadable,
+  contracts: Contract[],
+  filters: FacetFilter[] = [],
+): Promise<FacetCut[]> {
+  let addFacetCuts: FacetCut[] = [];
+  let replaceFacetCuts: FacetCut[] = [];
+  let removeFacetCuts: FacetCut[] = [];
+
+  try {
+    addFacetCuts = await addUnregisteredSelectors(diamond, contracts, filters);
+  } catch (error) {
+    console.log(`WARNING: ${(error as Error).message}`);
+  }
+
+  try {
+    replaceFacetCuts = await replaceRegisteredSelectors(
+      diamond,
+      contracts,
+      filters,
+    );
+  } catch (error) {
+    console.log(`WARNING: ${(error as Error).message}`);
+  }
+
+  try {
+    removeFacetCuts = await removeRegisteredSelectors(
+      diamond,
+      contracts,
+      filters,
+    );
+  } catch (error) {
+    console.log(`WARNING: ${(error as Error).message}`);
+  }
+
+  return groupFacetCuts([
+    ...addFacetCuts,
+    ...replaceFacetCuts,
+    ...removeFacetCuts,
+  ]);
+}
+
+// executes a DiamondCut using the provided FacetCut
+export async function diamondCut(
+  diamond: IDiamondWritable,
+  facetCut: FacetCut[],
+  target: string = AddressZero,
+  data: string = '0x',
+): Promise<ContractReceipt> {
+  return (await diamond.diamondCut(facetCut, target, data)).wait();
+}
+
+// groups facet cuts by target address and action type
+export function groupFacetCuts(facetCuts: FacetCut[]): FacetCut[] {
+  const cuts = facetCuts.reduce((acc: FacetCut[], facetCut: FacetCut) => {
+    if (acc.length == 0) acc.push(facetCut);
+
+    let exists = false;
+
+    acc.forEach((_, i) => {
+      if (
+        acc[i].action == facetCut.action &&
+        acc[i].target == facetCut.target
+      ) {
+        acc[i].selectors.push(...facetCut.selectors);
+        // removes duplicates, if there are any
+        acc[i].selectors = [...new Set(acc[i].selectors)];
+        exists = true;
+      }
+    });
+
+    // push facet cut if it does not already exist
+    if (!exists) acc.push(facetCut);
+
+    return acc;
+  }, []);
+
+  let cache: any = {};
+
+  // checks if selector is used multiple times, emits warning
+  cuts.forEach((cut) => {
+    cut.selectors.forEach((selector: string) => {
+      if (cache[selector]) {
+        console.log(
+          `WARNING: selector: ${selector}, target: ${cut.target} is defined in multiple cuts`,
+        );
+      } else {
+        cache[selector] = true;
+      }
+    });
+  });
+
+  return cuts;
+}
diff --git a/lib/index.ts b/lib/index.ts
index e6459ee4..6a4c3b7e 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -2,3 +2,4 @@ export * from './bn_conversion';
 export * from './erc20_permit';
 export * from './mocha_describe_filter';
 export * from './sign_data';
+export * from './diamond/utils';
diff --git a/lib/package.json b/lib/package.json
index 3f4ac877..b536e55e 100644
--- a/lib/package.json
+++ b/lib/package.json
@@ -25,6 +25,8 @@
     "tsc-clean": "tsc --build --clean tsconfig.json"
   },
   "dependencies": {
+    "@ethersproject/constants": "^5.7.0",
+    "@ethersproject/contracts": "^5.7.0",
     "eth-permit": "^0.1.10"
   },
   "files": [
diff --git a/spec/proxy/diamond/SolidStateDiamond.behavior.ts b/spec/proxy/diamond/SolidStateDiamond.behavior.ts
index 3326604b..aeffbf8c 100644
--- a/spec/proxy/diamond/SolidStateDiamond.behavior.ts
+++ b/spec/proxy/diamond/SolidStateDiamond.behavior.ts
@@ -24,7 +24,7 @@ import {
   MockContract,
 } from '@ethereum-waffle/mock-contract';
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers';
-import { describeFilter } from '@solidstate/library';
+import { describeFilter, FacetCutAction } from '@solidstate/library';
 import { ISolidStateDiamond } from '@solidstate/typechain-types';
 import { expect } from 'chai';
 import { ethers } from 'hardhat';
@@ -116,13 +116,17 @@ export function describeBehaviorOfSolidStateDiamond(
         const expectedSelectors = [];
 
         for (let selector of selectors) {
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: facet.address, action: 0, selectors: [selector] }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: facet.address,
+                action: FacetCutAction.ADD,
+                selectors: [selector],
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           expectedSelectors.push(selector);
 
@@ -152,7 +156,7 @@ export function describeBehaviorOfSolidStateDiamond(
         await instance
           .connect(owner)
           .diamondCut(
-            [{ target: facet.address, action: 0, selectors }],
+            [{ target: facet.address, action: FacetCutAction.ADD, selectors }],
             ethers.constants.AddressZero,
             '0x',
           );
@@ -164,7 +168,7 @@ export function describeBehaviorOfSolidStateDiamond(
             [
               {
                 target: ethers.constants.AddressZero,
-                action: 2,
+                action: FacetCutAction.REMOVE,
                 selectors: [selector],
               },
             ],
@@ -217,7 +221,7 @@ export function describeBehaviorOfSolidStateDiamond(
         await instance
           .connect(owner)
           .diamondCut(
-            [{ target: facet.address, action: 0, selectors }],
+            [{ target: facet.address, action: FacetCutAction.ADD, selectors }],
             ethers.constants.AddressZero,
             '0x',
           );
@@ -229,7 +233,7 @@ export function describeBehaviorOfSolidStateDiamond(
             [
               {
                 target: ethers.constants.AddressZero,
-                action: 2,
+                action: FacetCutAction.REMOVE,
                 selectors: [selector],
               },
             ],
@@ -282,7 +286,7 @@ export function describeBehaviorOfSolidStateDiamond(
         await instance
           .connect(owner)
           .diamondCut(
-            [{ target: facet.address, action: 0, selectors }],
+            [{ target: facet.address, action: FacetCutAction.ADD, selectors }],
             ethers.constants.AddressZero,
             '0x',
           );
@@ -294,7 +298,7 @@ export function describeBehaviorOfSolidStateDiamond(
             [
               {
                 target: ethers.constants.AddressZero,
-                action: 2,
+                action: FacetCutAction.REMOVE,
                 selectors: [selector],
               },
             ],
diff --git a/spec/proxy/diamond/writable/DiamondWritable.behavior.ts b/spec/proxy/diamond/writable/DiamondWritable.behavior.ts
index e87447d4..387984c2 100644
--- a/spec/proxy/diamond/writable/DiamondWritable.behavior.ts
+++ b/spec/proxy/diamond/writable/DiamondWritable.behavior.ts
@@ -1,7 +1,7 @@
 import { describeBehaviorOfERC165Base } from '../../../introspection';
 import { deployMockContract } from '@ethereum-waffle/mock-contract';
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers';
-import { describeFilter } from '@solidstate/library';
+import { describeFilter, FacetCutAction } from '@solidstate/library';
 import { IDiamondWritable } from '@solidstate/typechain-types';
 import { expect } from 'chai';
 import { ethers } from 'hardhat';
@@ -68,7 +68,7 @@ export function describeBehaviorOfDiamondWritable(
         const facets: any = [
           {
             target: facet.address,
-            action: 0,
+            action: FacetCutAction.ADD,
             selectors: [ethers.utils.hexlify(ethers.utils.randomBytes(4))],
           },
         ];
@@ -107,13 +107,17 @@ export function describeBehaviorOfDiamondWritable(
             );
           }
 
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: facet.address, action: 0, selectors }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: facet.address,
+                action: FacetCutAction.ADD,
+                selectors,
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           for (let fn of functions) {
             // call reverts, but with mock-specific message
@@ -130,7 +134,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: ethers.constants.AddressZero,
-                    action: 0,
+                    action: FacetCutAction.ADD,
                     selectors: [ethers.utils.randomBytes(4)],
                   },
                 ],
@@ -147,7 +151,7 @@ export function describeBehaviorOfDiamondWritable(
             const facetCuts = [
               {
                 target: facet.address,
-                action: 0,
+                action: FacetCutAction.ADD,
                 selectors: [ethers.utils.randomBytes(4)],
               },
             ];
@@ -176,13 +180,17 @@ export function describeBehaviorOfDiamondWritable(
             ethers.provider,
           );
 
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: facet.address, action: 0, selectors }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: facet.address,
+                action: FacetCutAction.ADD,
+                selectors,
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           for (let fn of functions) {
             // call reverts, but with mock-specific message
@@ -197,13 +205,17 @@ export function describeBehaviorOfDiamondWritable(
             expect(facetReplacement[fn]).not.to.be.undefined;
           }
 
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: facetReplacement.address, action: 1, selectors }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: facetReplacement.address,
+                action: FacetCutAction.REPLACE,
+                selectors,
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           for (let fn of functions) {
             // call reverts, but with mock-specific message
@@ -220,7 +232,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: ethers.constants.AddressZero,
-                    action: 1,
+                    action: FacetCutAction.REPLACE,
                     selectors: [ethers.utils.randomBytes(4)],
                   },
                 ],
@@ -239,7 +251,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: facet.address,
-                    action: 1,
+                    action: FacetCutAction.REPLACE,
                     selectors: [ethers.utils.randomBytes(4)],
                   },
                 ],
@@ -259,7 +271,7 @@ export function describeBehaviorOfDiamondWritable(
               [
                 {
                   target: instance.address,
-                  action: 0,
+                  action: FacetCutAction.ADD,
                   selectors: [selector],
                 },
               ],
@@ -272,7 +284,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: facet.address,
-                    action: 1,
+                    action: FacetCutAction.REPLACE,
                     selectors: [selector],
                   },
                 ],
@@ -292,7 +304,7 @@ export function describeBehaviorOfDiamondWritable(
               [
                 {
                   target: facet.address,
-                  action: 0,
+                  action: FacetCutAction.ADD,
                   selectors: [selector],
                 },
               ],
@@ -305,7 +317,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: facet.address,
-                    action: 1,
+                    action: FacetCutAction.REPLACE,
                     selectors: [selector],
                   },
                 ],
@@ -328,13 +340,17 @@ export function describeBehaviorOfDiamondWritable(
             ethers.provider,
           );
 
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: facet.address, action: 0, selectors }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: facet.address,
+                action: FacetCutAction.ADD,
+                selectors,
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           for (let fn of functions) {
             // call reverts, but with mock-specific message
@@ -343,13 +359,17 @@ export function describeBehaviorOfDiamondWritable(
             );
           }
 
-          await instance
-            .connect(owner)
-            .diamondCut(
-              [{ target: ethers.constants.AddressZero, action: 2, selectors }],
-              ethers.constants.AddressZero,
-              '0x',
-            );
+          await instance.connect(owner).diamondCut(
+            [
+              {
+                target: ethers.constants.AddressZero,
+                action: FacetCutAction.REMOVE,
+                selectors,
+              },
+            ],
+            ethers.constants.AddressZero,
+            '0x',
+          );
 
           for (let fn of functions) {
             await expect(
@@ -368,7 +388,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: instance.address,
-                    action: 2,
+                    action: FacetCutAction.REMOVE,
                     selectors: [ethers.utils.randomBytes(4)],
                   },
                 ],
@@ -387,7 +407,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: ethers.constants.AddressZero,
-                    action: 2,
+                    action: FacetCutAction.REMOVE,
                     selectors: [ethers.utils.randomBytes(4)],
                   },
                 ],
@@ -407,7 +427,7 @@ export function describeBehaviorOfDiamondWritable(
               [
                 {
                   target: instance.address,
-                  action: 0,
+                  action: FacetCutAction.ADD,
                   selectors: [selector],
                 },
               ],
@@ -420,7 +440,7 @@ export function describeBehaviorOfDiamondWritable(
                 [
                   {
                     target: ethers.constants.AddressZero,
-                    action: 2,
+                    action: FacetCutAction.REMOVE,
                     selectors: [selector],
                   },
                 ],
@@ -466,7 +486,7 @@ export function describeBehaviorOfDiamondWritable(
               [
                 {
                   target: ethers.constants.AddressZero,
-                  action: 0,
+                  action: FacetCutAction.ADD,
                   selectors: [],
                 },
               ],
diff --git a/test/proxy/diamond/SolidStateDiamond.ts b/test/proxy/diamond/SolidStateDiamond.ts
index 508e8e41..b9766414 100644
--- a/test/proxy/diamond/SolidStateDiamond.ts
+++ b/test/proxy/diamond/SolidStateDiamond.ts
@@ -1,4 +1,5 @@
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers';
+import { FacetCutAction } from '@solidstate/library';
 import { describeBehaviorOfSolidStateDiamond } from '@solidstate/spec';
 import {
   SolidStateDiamond,
@@ -30,7 +31,7 @@ describe('SolidStateDiamond', function () {
 
     facetCuts[0] = {
       target: instance.address,
-      action: 0,
+      action: FacetCutAction.ADD,
       selectors: facets[0].selectors,
     };
   });
diff --git a/test/proxy/diamond/base/DiamondBase.ts b/test/proxy/diamond/base/DiamondBase.ts
index f317eba6..cf874d68 100644
--- a/test/proxy/diamond/base/DiamondBase.ts
+++ b/test/proxy/diamond/base/DiamondBase.ts
@@ -1,3 +1,4 @@
+import { FacetCutAction } from '@solidstate/library';
 import { describeBehaviorOfDiamondBase } from '@solidstate/spec';
 import {
   DiamondBaseMock,
@@ -18,7 +19,7 @@ describe('DiamondBase', function () {
     instance = await new DiamondBaseMock__factory(deployer).deploy([
       {
         target: facetInstance.address,
-        action: 0,
+        action: FacetCutAction.ADD,
         selectors: [facetInstance.interface.getSighash('owner()')],
       },
     ]);
diff --git a/test/proxy/diamond/fallback/DiamondFallback.ts b/test/proxy/diamond/fallback/DiamondFallback.ts
index 75404ead..6734f557 100644
--- a/test/proxy/diamond/fallback/DiamondFallback.ts
+++ b/test/proxy/diamond/fallback/DiamondFallback.ts
@@ -1,4 +1,5 @@
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers';
+import { FacetCutAction } from '@solidstate/library';
 import { describeBehaviorOfDiamondFallback } from '@solidstate/spec';
 import {
   DiamondFallbackMock,
@@ -25,7 +26,7 @@ describe('DiamondFallback', function () {
     instance = await new DiamondFallbackMock__factory(deployer).deploy([
       {
         target: facetInstance.address,
-        action: 0,
+        action: FacetCutAction.ADD,
         selectors: [facetInstance.interface.getSighash('owner()')],
       },
     ]);
diff --git a/test/proxy/diamond/readable/DiamondReadable.ts b/test/proxy/diamond/readable/DiamondReadable.ts
index 6c75969a..3e1eb98c 100644
--- a/test/proxy/diamond/readable/DiamondReadable.ts
+++ b/test/proxy/diamond/readable/DiamondReadable.ts
@@ -1,4 +1,5 @@
 import { deployMockContract } from '@ethereum-waffle/mock-contract';
+import { FacetCutAction } from '@solidstate/library';
 import { describeBehaviorOfDiamondReadable } from '@solidstate/spec';
 import {
   DiamondReadableMock,
@@ -35,7 +36,7 @@ describe('DiamondReadable', function () {
 
     facetCuts.push({
       target: facet.address,
-      action: 0,
+      action: FacetCutAction.ADD,
       selectors,
     });
   });