diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index dbc1ca909a2..cf7ce587f36 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4431,9 +4431,9 @@ static bool isTruncateOf(SelectionDAG &DAG, SDValue N, SDValue &Op,
 
   ConstantSDNode *COp0 = dyn_cast<ConstantSDNode>(Op0);
   ConstantSDNode *COp1 = dyn_cast<ConstantSDNode>(Op1);
-  if (COp0 && COp0->getZExtValue() == 0)
+  if (COp0 && COp0->isNullValue())
     Op = Op1;
-  else if (COp1 && COp1->getZExtValue() == 0)
+  else if (COp1 && COp1->isNullValue())
     Op = Op0;
   else
     return false;
diff --git a/test/CodeGen/Generic/pr12507.ll b/test/CodeGen/Generic/pr12507.ll
new file mode 100644
index 00000000000..c7933585060
--- /dev/null
+++ b/test/CodeGen/Generic/pr12507.ll
@@ -0,0 +1,18 @@
+; RUN: llc < %s
+
+@c = external global i32, align 4
+
+define void @foo(i160 %x) {
+entry:
+  %cmp.i = icmp ne i160 %x, 340282366920938463463374607431768211456
+  %conv.i = zext i1 %cmp.i to i32
+  %tobool.i = icmp eq i32 %conv.i, 0
+  br i1 %tobool.i, label %if.then.i, label %fn1.exit
+
+if.then.i:
+  store i32 0, i32* @c, align 4
+  br label %fn1.exit
+
+fn1.exit:
+  ret void
+}