diff --git a/libguile/stacks.c b/libguile/stacks.c
index 63bbda07b..61c262453 100644
--- a/libguile/stacks.c
+++ b/libguile/stacks.c
@@ -360,7 +360,10 @@ narrow_stack (SCM stack,int inner,SCM inner_key,int outer,SCM outer_key)
 	  SCM m = s->frames[i].source;
 	  if (   SCM_MEMOIZEDP (m)
 	      && SCM_NIMP (SCM_MEMOIZED_ENV (m))
-	      && SCM_FALSEP (scm_system_module_env_p (SCM_MEMOIZED_ENV (m))))
+#if SCM_DEBUG_DEPRECATED == 0
+	      && SCM_FALSEP (scm_system_module_env_p (SCM_MEMOIZED_ENV (m)))
+#endif
+		 )
 	    {
 	      /* Back up in order to include any non-source frames */
 	      while (i > 0