diff --git a/cel/env.go b/cel/env.go
index ea5597e2..3bfe4289 100644
--- a/cel/env.go
+++ b/cel/env.go
@@ -217,7 +217,7 @@ func (e *Env) Check(ast *Ast) (*Ast, *Issues) {
 	chk, err := e.initChecker()
 	if err != nil {
 		errs := common.NewErrors(ast.Source())
-		errs.ReportError(common.NoLocation, err.Error())
+		errs.ReportErrorString(common.NoLocation, err.Error())
 		return nil, NewIssuesWithSourceInfo(errs, ast.NativeRep().SourceInfo())
 	}
 
diff --git a/cel/library.go b/cel/library.go
index 3dc8594b..e36590e2 100644
--- a/cel/library.go
+++ b/cel/library.go
@@ -731,7 +731,7 @@ var (
 func timestampGetFullYear(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Year())
 }
@@ -739,7 +739,7 @@ func timestampGetFullYear(ts, tz ref.Val) ref.Val {
 func timestampGetMonth(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	// CEL spec indicates that the month should be 0-based, but the Time value
 	// for Month() is 1-based.
@@ -749,7 +749,7 @@ func timestampGetMonth(ts, tz ref.Val) ref.Val {
 func timestampGetDayOfYear(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.YearDay() - 1)
 }
@@ -757,7 +757,7 @@ func timestampGetDayOfYear(ts, tz ref.Val) ref.Val {
 func timestampGetDayOfMonthZeroBased(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Day() - 1)
 }
@@ -765,7 +765,7 @@ func timestampGetDayOfMonthZeroBased(ts, tz ref.Val) ref.Val {
 func timestampGetDayOfMonthOneBased(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Day())
 }
@@ -773,7 +773,7 @@ func timestampGetDayOfMonthOneBased(ts, tz ref.Val) ref.Val {
 func timestampGetDayOfWeek(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Weekday())
 }
@@ -781,7 +781,7 @@ func timestampGetDayOfWeek(ts, tz ref.Val) ref.Val {
 func timestampGetHours(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Hour())
 }
@@ -789,7 +789,7 @@ func timestampGetHours(ts, tz ref.Val) ref.Val {
 func timestampGetMinutes(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Minute())
 }
@@ -797,7 +797,7 @@ func timestampGetMinutes(ts, tz ref.Val) ref.Val {
 func timestampGetSeconds(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Second())
 }
@@ -805,7 +805,7 @@ func timestampGetSeconds(ts, tz ref.Val) ref.Val {
 func timestampGetMilliseconds(ts, tz ref.Val) ref.Val {
 	t, err := inTimeZone(ts, tz)
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(t.Nanosecond() / 1000000)
 }
diff --git a/common/errors.go b/common/errors.go
index 89570683..c8865df8 100644
--- a/common/errors.go
+++ b/common/errors.go
@@ -46,6 +46,11 @@ func (e *Errors) ReportError(l Location, format string, args ...any) {
 	e.ReportErrorAtID(0, l, format, args...)
 }
 
+// ReportErrorString records an error at a source location.
+func (e *Errors) ReportErrorString(l Location, message string) {
+	e.ReportErrorAtID(0, l, "%s", message)
+}
+
 // ReportErrorAtID records an error at a source location and expression id.
 func (e *Errors) ReportErrorAtID(id int64, l Location, format string, args ...any) {
 	e.numErrors++
diff --git a/common/types/err.go b/common/types/err.go
index 9c9d9e21..ee1a76e7 100644
--- a/common/types/err.go
+++ b/common/types/err.go
@@ -62,6 +62,12 @@ func NewErr(format string, args ...any) ref.Val {
 	return &Err{error: fmt.Errorf(format, args...)}
 }
 
+// NewErr creates a new Err with the provided message.
+// TODO: Audit the use of this function and standardize the error messages and codes.
+func NewErrFromString(message string) ref.Val {
+	return &Err{error: errors.New(message)}
+}
+
 // NewErrWithNodeID creates a new Err described by the format string and args.
 // TODO: Audit the use of this function and standardize the error messages and codes.
 func NewErrWithNodeID(id int64, format string, args ...any) ref.Val {
diff --git a/common/types/list.go b/common/types/list.go
index ca47d39f..7e68a5da 100644
--- a/common/types/list.go
+++ b/common/types/list.go
@@ -243,7 +243,7 @@ func (l *baseList) Equal(other ref.Val) ref.Val {
 func (l *baseList) Get(index ref.Val) ref.Val {
 	ind, err := IndexOrError(index)
 	if err != nil {
-		return ValOrErr(index, err.Error())
+		return ValOrErr(index, "%v", err)
 	}
 	if ind < 0 || ind >= l.size {
 		return NewErr("index '%d' out of range in list size '%d'", ind, l.Size())
@@ -427,7 +427,7 @@ func (l *concatList) Equal(other ref.Val) ref.Val {
 func (l *concatList) Get(index ref.Val) ref.Val {
 	ind, err := IndexOrError(index)
 	if err != nil {
-		return ValOrErr(index, err.Error())
+		return ValOrErr(index, "%v", err)
 	}
 	i := Int(ind)
 	if i < l.prevList.Size().(Int) {
diff --git a/common/types/object.go b/common/types/object.go
index 8ba0af9f..5377bff8 100644
--- a/common/types/object.go
+++ b/common/types/object.go
@@ -151,7 +151,7 @@ func (o *protoObj) Get(index ref.Val) ref.Val {
 	}
 	fv, err := fd.GetFrom(o.value)
 	if err != nil {
-		return NewErr(err.Error())
+		return NewErrFromString(err.Error())
 	}
 	return o.NativeToValue(fv)
 }
diff --git a/ext/formatting.go b/ext/formatting.go
index dbff613b..932d562e 100644
--- a/ext/formatting.go
+++ b/ext/formatting.go
@@ -434,7 +434,7 @@ func (stringFormatValidator) Validate(env *cel.Env, _ cel.ValidatorConfig, a *as
 		// use a placeholder locale, since locale doesn't affect syntax
 		_, err := parseFormatString(formatStr, formatCheck, formatCheck, "en_US")
 		if err != nil {
-			iss.ReportErrorAtID(getErrorExprID(e.ID(), err), err.Error())
+			iss.ReportErrorAtID(getErrorExprID(e.ID(), err), "%v", err)
 			continue
 		}
 		seenArgs := formatCheck.argsRequested
diff --git a/ext/guards.go b/ext/guards.go
index ccede289..1461c041 100644
--- a/ext/guards.go
+++ b/ext/guards.go
@@ -24,28 +24,28 @@ import (
 
 func intOrError(i int64, err error) ref.Val {
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Int(i)
 }
 
 func bytesOrError(bytes []byte, err error) ref.Val {
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.Bytes(bytes)
 }
 
 func stringOrError(str string, err error) ref.Val {
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.String(str)
 }
 
 func listStringOrError(strs []string, err error) ref.Val {
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return types.DefaultTypeAdapter.NativeToValue(strs)
 }
diff --git a/ext/native.go b/ext/native.go
index 83f36589..1c33def4 100644
--- a/ext/native.go
+++ b/ext/native.go
@@ -343,7 +343,7 @@ func (tp *nativeTypeProvider) NewValue(typeName string, fields map[string]ref.Va
 		}
 		fieldVal, err := val.ConvertToNative(refFieldDef.Type)
 		if err != nil {
-			return types.NewErr(err.Error())
+			return types.NewErrFromString(err.Error())
 		}
 		refField := refVal.FieldByIndex(refFieldDef.Index)
 		refFieldVal := reflect.ValueOf(fieldVal)
@@ -450,7 +450,7 @@ func convertToCelType(refType reflect.Type) (*cel.Type, bool) {
 func (tp *nativeTypeProvider) newNativeObject(val any, refValue reflect.Value) ref.Val {
 	valType, err := newNativeType(tp.options.fieldNameHandler, refValue.Type())
 	if err != nil {
-		return types.NewErr(err.Error())
+		return types.NewErrFromString(err.Error())
 	}
 	return &nativeObj{
 		Adapter:  tp,
diff --git a/interpreter/attributes_test.go b/interpreter/attributes_test.go
index b89b2214..86b6025f 100644
--- a/interpreter/attributes_test.go
+++ b/interpreter/attributes_test.go
@@ -1120,7 +1120,7 @@ func TestAttributeStateTracking(t *testing.T) {
 			}
 			parsed, errors := p.Parse(src)
 			if len(errors.GetErrors()) != 0 {
-				t.Fatalf(errors.ToDisplayString())
+				t.Fatal(errors.ToDisplayString())
 			}
 			cont := containers.DefaultContainer
 			reg := newTestRegistry(t)
@@ -1135,7 +1135,7 @@ func TestAttributeStateTracking(t *testing.T) {
 			}
 			checked, errors := checker.Check(parsed, src, env)
 			if len(errors.GetErrors()) != 0 {
-				t.Fatalf(errors.ToDisplayString())
+				t.Fatal(errors.ToDisplayString())
 			}
 			in, err := NewActivation(tc.in)
 			if err != nil {
diff --git a/interpreter/interpreter_test.go b/interpreter/interpreter_test.go
index 00bf04dc..8582b6bc 100644
--- a/interpreter/interpreter_test.go
+++ b/interpreter/interpreter_test.go
@@ -1780,7 +1780,7 @@ func TestInterpreter_SetProto2PrimitiveFields(t *testing.T) {
 			types.NewObjectType("google.expr.proto2.test.TestAllTypes")))
 	checked, errors := checker.Check(parsed, src, env)
 	if len(errors.GetErrors()) != 0 {
-		t.Errorf(errors.ToDisplayString())
+		t.Error(errors.ToDisplayString())
 	}
 
 	attrs := NewAttributeFactory(cont, reg, reg)
@@ -1829,7 +1829,7 @@ func TestInterpreter_MissingIdentInSelect(t *testing.T) {
 	env.AddIdents(decls.NewVariable("a.b", types.DynType))
 	checked, errors := checker.Check(parsed, src, env)
 	if len(errors.GetErrors()) != 0 {
-		t.Fatalf(errors.ToDisplayString())
+		t.Fatal(errors.ToDisplayString())
 	}
 
 	attrs := NewPartialAttributeFactory(cont, reg, reg)
@@ -1885,7 +1885,7 @@ func TestInterpreter_TypeConversionOpt(t *testing.T) {
 		env := newTestEnv(t, cont, reg)
 		checked, errors := checker.Check(parsed, src, env)
 		if len(errors.GetErrors()) != 0 {
-			t.Fatalf(errors.ToDisplayString())
+			t.Fatal(errors.ToDisplayString())
 		}
 		attrs := NewAttributeFactory(cont, reg, reg)
 		interp := newStandardInterpreter(t, cont, reg, reg, attrs)
diff --git a/parser/errors.go b/parser/errors.go
index 93ae7a3a..c3cec01a 100644
--- a/parser/errors.go
+++ b/parser/errors.go
@@ -15,8 +15,6 @@
 package parser
 
 import (
-	"fmt"
-
 	"github.com/google/cel-go/common"
 )
 
@@ -31,11 +29,11 @@ func (e *parseErrors) errorCount() int {
 }
 
 func (e *parseErrors) internalError(message string) {
-	e.errs.ReportErrorAtID(0, common.NoLocation, message)
+	e.errs.ReportErrorAtID(0, common.NoLocation, "%s", message)
 }
 
 func (e *parseErrors) syntaxError(l common.Location, message string) {
-	e.errs.ReportErrorAtID(0, l, fmt.Sprintf("Syntax error: %s", message))
+	e.errs.ReportErrorAtID(0, l, "Syntax error: %s", message)
 }
 
 func (e *parseErrors) reportErrorAtID(id int64, l common.Location, message string, args ...any) {
diff --git a/parser/parser.go b/parser/parser.go
index a77213b1..cbe80051 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -970,7 +970,7 @@ func (p *parser) expandMacro(exprID int64, function string, target ast.Expr, arg
 			loc = p.helper.getLocation(exprID)
 		}
 		p.helper.deleteID(exprID)
-		return p.reportError(loc, err.Message), true
+		return p.reportError(loc, "%s", err.Message), true
 	}
 	// A nil value from the macro indicates that the macro implementation decided that
 	// an expansion should not be performed.
diff --git a/parser/parser_test.go b/parser/parser_test.go
index ed72b378..887df6c3 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -2039,7 +2039,7 @@ func TestParse(t *testing.T) {
 				if tc.E == "" {
 					t.Fatalf("Unexpected errors: %v", actualErr)
 				} else if !test.Compare(actualErr, tc.E) {
-					t.Fatalf(test.DiffMessage("Error mismatch", actualErr, tc.E))
+					t.Fatal(test.DiffMessage("Error mismatch", actualErr, tc.E))
 				}
 				return
 			} else if tc.E != "" {
diff --git a/repl/typefmt.go b/repl/typefmt.go
index a25ff679..cf1b6ed5 100644
--- a/repl/typefmt.go
+++ b/repl/typefmt.go
@@ -312,7 +312,7 @@ func ParseType(t string) (*exprpb.Type, error) {
 		for i, e := range errs {
 			msgs[i] = e.Error()
 		}
-		err = fmt.Errorf("errors parsing type:\n" + strings.Join(msgs, "\n"))
+		err = fmt.Errorf("errors parsing type:\n%s", strings.Join(msgs, "\n"))
 	}
 
 	return result, err