diff --git a/skeletons/UniversalString.c b/skeletons/UniversalString.c
index f3279b4..2918d07 100644
--- a/skeletons/UniversalString.c
+++ b/skeletons/UniversalString.c
@@ -5,6 +5,7 @@
 #include <asn_internal.h>
 #include <UniversalString.h>
 #include <UTF8String.h>
+#include <assert.h>
 
 /*
  * UniversalString basic type description.