diff --git a/theta/a_not_b.go b/theta/a_not_b.go
index 6a9a921..1224f96 100644
--- a/theta/a_not_b.go
+++ b/theta/a_not_b.go
@@ -18,7 +18,6 @@
 package theta
 
 import (
-	"errors"
 	"fmt"
 	"slices"
 
@@ -118,7 +117,7 @@ func computeHashBased(a, b Sketch, theta uint64) ([]uint64, error) {
 	for entry := range b.All() {
 		if entry < theta {
 			idx, err := table.Find(entry)
-			if err != nil && errors.Is(err, ErrKeyNotFoundAndNoEmptySlots) {
+			if err != nil && err == ErrKeyNotFoundAndNoEmptySlots {
 				return nil, err
 			}
 
@@ -133,7 +132,7 @@ func computeHashBased(a, b Sketch, theta uint64) ([]uint64, error) {
 	for entry := range a.All() {
 		if entry < theta {
 			_, err := table.Find(entry)
-			if err != nil && errors.Is(err, ErrKeyNotFound) {
+			if err != nil && err == ErrKeyNotFound {
 				entries = append(entries, entry)
 			}
 		} else if a.IsOrdered() {
diff --git a/theta/intersection.go b/theta/intersection.go
index 7c34536..a329efb 100644
--- a/theta/intersection.go
+++ b/theta/intersection.go
@@ -177,7 +177,7 @@ func (i *Intersection) Update(sketch Sketch) error {
 		i.hashtable = NewHashtable(lgSize, lgSize-1, ResizeX1, 1.0, i.hashtable.theta, i.hashtable.seed, i.hashtable.isEmpty)
 		for j := 0; j < matchCount; j++ {
 			key, err := i.hashtable.Find(matchesEntries[j])
-			if err != nil && errors.Is(err, ErrKeyNotFoundAndNoEmptySlots) {
+			if err != nil && err == ErrKeyNotFoundAndNoEmptySlots {
 				return err
 			}
 
diff --git a/theta/union.go b/theta/union.go
index 480781c..b501639 100644
--- a/theta/union.go
+++ b/theta/union.go
@@ -136,7 +136,7 @@ func (u *Union) Update(sketch Sketch) error {
 		if entry < u.theta && entry < u.hashtable.theta {
 			index, err := u.hashtable.Find(entry)
 			if err != nil {
-				if errors.Is(err, ErrKeyNotFound) {
+				if err == ErrKeyNotFound {
 					u.hashtable.Insert(index, entry)
 					continue
 				}
diff --git a/theta/update_sketch.go b/theta/update_sketch.go
index 4540f72..03a4028 100644
--- a/theta/update_sketch.go
+++ b/theta/update_sketch.go
@@ -266,7 +266,7 @@ func (s *QuickSelectUpdateSketch) UpdateInt64(value int64) error {
 
 	index, err := s.table.Find(hash)
 	if err != nil {
-		if errors.Is(err, ErrKeyNotFound) {
+		if err == ErrKeyNotFound {
 			s.table.Insert(index, hash)
 			return nil
 		}
@@ -292,7 +292,7 @@ func (s *QuickSelectUpdateSketch) UpdateInt32(value int32) error {
 
 	index, err := s.table.Find(hash)
 	if err != nil {
-		if errors.Is(err, ErrKeyNotFound) {
+		if err == ErrKeyNotFound {
 			s.table.Insert(index, hash)
 			return nil
 		}
@@ -362,7 +362,7 @@ func (s *QuickSelectUpdateSketch) UpdateString(value string) error {
 
 	index, err := s.table.Find(hash)
 	if err != nil {
-		if errors.Is(err, ErrKeyNotFound) {
+		if err == ErrKeyNotFound {
 			s.table.Insert(index, hash)
 			return nil
 		}
@@ -382,7 +382,7 @@ func (s *QuickSelectUpdateSketch) UpdateBytes(data []byte) error {
 
 	index, err := s.table.Find(hash)
 	if err != nil {
-		if errors.Is(err, ErrKeyNotFound) {
+		if err == ErrKeyNotFound {
 			s.table.Insert(index, hash)
 			return nil
 		}