diff --git a/compiler/debug-dump.lisp b/compiler/debug-dump.lisp
index 11d1a9c80fbf48985694b9dd496a4d659f3e7e74..957774dd34ae921689ce8a596e1d9d5d1312e117 100644
--- a/compiler/debug-dump.lisp
+++ b/compiler/debug-dump.lisp
@@ -295,9 +295,8 @@
 		       (setf (debug-source-name res) name))
 		      (t
 		       (setf (debug-source-from res) name)
-		       (when (eq name :lisp)
-			 (setf (debug-source-name res)
-			       (aref (file-info-forms x) 0)))))
+		       (setf (debug-source-name res)
+			     (coerce (file-info-forms x) 'simple-vector))))
 		res))
 	  (source-info-files info)))