diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 23750e3751a..db525b47c70 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2004-08-02  Roger Sayle  <roger@eyesopen.com>
+
+	* fold-const.c (fold) <TRUNC_MOD_EXPR>: The transformation "X % -Y"
+	-> "X % Y" is only valid for TRUNC_MOD_EXPR.
+
 2004-08-02  Gabriel Dos Reis  <gdr@integrable-solutions.net>
 
 	* vec.h (DEF_VEC_P): Add proper cast to uses of vec_o_reserve and
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 23f7576ff4e..f4a6fb022d4 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7624,8 +7624,9 @@ fold (tree expr)
 			       fold_convert (type, arg0), mask));
 	}
 
-      /* X % -C is the same as X % C (for all rounding moduli).  */
-      if (!TYPE_UNSIGNED (type)
+      /* X % -C is the same as X % C.  */
+      if (code == TRUNC_MOD_EXPR
+	  && !TYPE_UNSIGNED (type)
 	  && TREE_CODE (arg1) == INTEGER_CST
 	  && TREE_INT_CST_HIGH (arg1) < 0
 	  && !flag_trapv
@@ -7634,8 +7635,9 @@ fold (tree expr)
 	return fold (build2 (code, type, fold_convert (type, arg0),
 			     fold_convert (type, negate_expr (arg1))));
 
-      /* X % -Y is the same as X % Y (for all rounding moduli).  */
-      if (!TYPE_UNSIGNED (type)
+      /* X % -Y is the same as X % Y.  */
+      if (code == TRUNC_MOD_EXPR
+	  && !TYPE_UNSIGNED (type)
 	  && TREE_CODE (arg1) == NEGATE_EXPR
 	  && !flag_trapv)
 	return fold (build2 (code, type, fold_convert (type, arg0),