diff --git a/lib/AST/ByteCode/InterpBuiltin.cpp b/lib/AST/ByteCode/InterpBuiltin.cpp
index d418e0a..91deda9 100644
--- a/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -300,6 +300,9 @@
   if (!CheckDummy(S, OpPC, StrPtr.block(), AK_Read))
     return false;
 
+  if (!StrPtr.getFieldDesc()->isPrimitiveArray())
+    return false;
+
   assert(StrPtr.getFieldDesc()->isPrimitiveArray());
   unsigned ElemSize = StrPtr.getFieldDesc()->getElemSize();
 
diff --git a/test/AST/ByteCode/builtins.c b/test/AST/ByteCode/builtins.c
new file mode 100644
index 0000000..a51260c
--- /dev/null
+++ b/test/AST/ByteCode/builtins.c
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter %s -verify
+// RUN: %clang_cc1                                         %s -verify=ref
+
+// expected-no-diagnostics
+// ref-no-diagnostics
+
+extern __SIZE_TYPE__ strlen(const char *);
+
+struct str_t {
+  char s1[sizeof("a")];
+};
+static const struct str_t str1 = {"a"};
+#define str ((const char *)&str1)
+int structStrlen(void) {
+  if (strlen(str) == 1)
+    return 0;
+  return 1;
+}
+