diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 94725d93bcc7..a008d0dcfed9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2008-03-30  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/31023
+	* fold-const.c (fold_sign_changed_comparison): Do leave
+	conversions to base-types alone.
+
 2008-03-29  Andrew Pinski  <andrew_pinski@playstation.sony.com>
 
 	* config/rs6000/rs6000.c (rs6000_stack_info): Don't force saving of
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 5d5d7cf2b976..c420b79b75c5 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -6807,6 +6807,11 @@ fold_sign_changed_comparison (enum tree_code code, tree type,
   if (TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
     return NULL_TREE;
 
+  /* If the conversion is from an integral subtype to its basetype
+     leave it alone.  */
+  if (TREE_TYPE (inner_type) == outer_type)
+    return NULL_TREE;
+
   if (TREE_CODE (arg1) != INTEGER_CST
       && !((TREE_CODE (arg1) == NOP_EXPR
 	    || TREE_CODE (arg1) == CONVERT_EXPR)