diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index af1121e3c73..813d06cf643 100644
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -3782,7 +3782,7 @@ void Verifier::verifyTypeRefs() {
   for (auto *CU : CUs->operands())
     if (auto Ts = cast<DICompileUnit>(CU)->getRetainedTypes())
       for (DIType *Op : Ts)
-        if (auto *T = dyn_cast<DICompositeType>(Op))
+        if (auto *T = dyn_cast_or_null<DICompositeType>(Op))
           if (auto *S = T->getRawIdentifier()) {
             UnresolvedTypeRefs.erase(S);
             TypeRefs.insert(std::make_pair(S, T));
diff --git a/test/Verifier/dbg-null-retained-type.ll b/test/Verifier/dbg-null-retained-type.ll
new file mode 100644
index 00000000000..f0368c8c487
--- /dev/null
+++ b/test/Verifier/dbg-null-retained-type.ll
@@ -0,0 +1,10 @@
+; RUN: not llvm-as -disable-output <%s 2>&1 | FileCheck %s
+; CHECK:      assembly parsed, but does not verify
+; CHECK-NEXT: invalid retained type
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!llvm.dbg.cu = !{!1}
+!1 = distinct !DICompileUnit(file: !2, language: DW_LANG_C99, retainedTypes: !3)
+!2 = !DIFile(filename: "file.c", directory: "/path/to/dir")
+!3 = !{null}