diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 300821026a7..55a10d716b9 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -581,7 +581,7 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
       if (NumOps == 2 &&
           cast<PointerType>(ResultTy)->getElementType()->isIntegerTy(8)) {
         ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]);
-        assert(CE->getType() == IntPtrTy &&
+        assert((CE == 0 || CE->getType() == IntPtrTy) &&
                "CastGEPIndices didn't canonicalize index types!");
         if (CE && CE->getOpcode() == Instruction::Sub &&
             CE->getOperand(0)->isNullValue()) {
diff --git a/test/Transforms/InstCombine/crash.ll b/test/Transforms/InstCombine/crash.ll
index e87a30254e6..e8babc3a1ee 100644
--- a/test/Transforms/InstCombine/crash.ll
+++ b/test/Transforms/InstCombine/crash.ll
@@ -341,3 +341,15 @@ define double @test16(i32 %a) nounwind {
   %select = select i1 %cmp, double 2.000000e+00, double 3.141592e+00
   ret double %select
 }
+
+
+; PR8983
+%struct.basic_ios = type { i8 }
+
+define %struct.basic_ios *@test17() ssp {
+entry:
+  %add.ptr.i = getelementptr i8* null, i64 undef
+  %0 = bitcast i8* %add.ptr.i to %struct.basic_ios*
+  ret %struct.basic_ios* %0
+}
+