diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index c40c45ed840..f41d5031365 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -3243,12 +3243,12 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       poly_int64 extra_off = 0;
       if (j == 0 && i >= 0
 	  && lhs_ops[0].opcode == MEM_REF
-	  && known_ne (lhs_ops[0].off, -1))
+	  && maybe_ne (lhs_ops[0].off, -1))
 	{
 	  if (known_eq (lhs_ops[0].off, vr->operands[i].off))
 	    i--, j--;
 	  else if (vr->operands[i].opcode == MEM_REF
-		   && known_ne (vr->operands[i].off, -1))
+		   && maybe_ne (vr->operands[i].off, -1))
 	    {
 	      extra_off = vr->operands[i].off - lhs_ops[0].off;
 	      i--, j--;