diff --git a/src/api/api_ast_vector.cpp b/src/api/api_ast_vector.cpp
index 5fe19a7d5..335fb6170 100644
--- a/src/api/api_ast_vector.cpp
+++ b/src/api/api_ast_vector.cpp
@@ -48,7 +48,8 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_ast_vector_dec_ref(c, v);
         RESET_ERROR_CODE();
-        to_ast_vector(v)->dec_ref();
+        if (v) 
+            to_ast_vector(v)->dec_ref();
         Z3_CATCH;
     }