diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ae1d9b5c0f7..01f77cbfa87 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2013-05-24  Alexander Ivchenko  <alexander.ivchenko@intel.com>
+
+	PR tree-ssa/57385
+	* tree-ssa-sccvn.c (fully_constant_vn_reference_p): Check
+	that index is not negative.
+
 2013-05-24  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR rtl-optimization/55177
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f9ef3c062a7..ca359e4ef68 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-05-24  Alexander Ivchenko  <alexander.ivchenko@intel.com>
+
+	PR tree-ssa/57385
+	* gcc.dg/tree-ssa/pr57385.c: New test.
+
 2013-05-24  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/derived_type4.adb: New test.
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 49d61b0c239..0e7a74c2a9c 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1294,6 +1294,7 @@ fully_constant_vn_reference_p (vn_reference_t ref)
 	      == TYPE_MODE (TREE_TYPE (TREE_TYPE (arg0->op0))))
 	  && GET_MODE_CLASS (TYPE_MODE (op->type)) == MODE_INT
 	  && GET_MODE_SIZE (TYPE_MODE (op->type)) == 1
+	  && tree_int_cst_sgn (op->op0) >= 0
 	  && compare_tree_int (op->op0, TREE_STRING_LENGTH (arg0->op0)) < 0)
 	return build_int_cst_type (op->type,
 				   (TREE_STRING_POINTER (arg0->op0)