diff --git a/internal/impl/pointer_reflect.go b/internal/impl/pointer_reflect.go
index 0b62f6c..055c322 100644
--- a/internal/impl/pointer_reflect.go
+++ b/internal/impl/pointer_reflect.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build purego
+// +build purego appengine
 
 package impl
 
diff --git a/internal/impl/pointer_unsafe.go b/internal/impl/pointer_unsafe.go
index fc77cfc..16078bd 100644
--- a/internal/impl/pointer_unsafe.go
+++ b/internal/impl/pointer_unsafe.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !purego
+// +build !purego,!appengine
 
 package impl
 
diff --git a/reflect/protoreflect/value_pure.go b/reflect/protoreflect/value_pure.go
index 4a13564..a52ce47 100644
--- a/reflect/protoreflect/value_pure.go
+++ b/reflect/protoreflect/value_pure.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build purego
+// +build purego appengine
 
 package protoreflect
 
diff --git a/reflect/protoreflect/value_unsafe.go b/reflect/protoreflect/value_unsafe.go
index ca911f6..64e0419 100644
--- a/reflect/protoreflect/value_unsafe.go
+++ b/reflect/protoreflect/value_unsafe.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !purego
+// +build !purego,!appengine
 
 package protoreflect
 
diff --git a/reflect/prototype/name_pure.go b/reflect/prototype/name_pure.go
index 6d943b3..3720729 100644
--- a/reflect/prototype/name_pure.go
+++ b/reflect/prototype/name_pure.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build purego
+// +build purego appengine
 
 package prototype
 
diff --git a/reflect/prototype/name_unsafe.go b/reflect/prototype/name_unsafe.go
index 43a6c7e..27b22ad 100644
--- a/reflect/prototype/name_unsafe.go
+++ b/reflect/prototype/name_unsafe.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !purego
+// +build !purego,!appengine
 
 package prototype