diff --git a/clang/lib/Headers/intrin.h b/clang/lib/Headers/intrin.h
index 34ec79d6acbc6..4803277472ee8 100644
--- a/clang/lib/Headers/intrin.h
+++ b/clang/lib/Headers/intrin.h
@@ -97,8 +97,9 @@ unsigned long __readcr8(void);
 unsigned int __readdr(unsigned int);
 #ifdef __i386__
 unsigned char __readfsbyte(unsigned long);
-unsigned __int64 __readfsqword(unsigned long);
 unsigned short __readfsword(unsigned long);
+unsigned long __readfsdword(unsigned long);
+unsigned __int64 __readfsqword(unsigned long);
 #endif
 unsigned __int64 __readmsr(unsigned long);
 unsigned __int64 __readpmc(unsigned long);
diff --git a/clang/test/CodeGen/X86/ms-x86-intrinsics.c b/clang/test/CodeGen/X86/ms-x86-intrinsics.c
index 6f745ff00f54e..0eca455bb5c32 100644
--- a/clang/test/CodeGen/X86/ms-x86-intrinsics.c
+++ b/clang/test/CodeGen/X86/ms-x86-intrinsics.c
@@ -1,10 +1,12 @@
-// RUN: %clang_cc1 -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 \
+// RUN: %clang_cc1 -Werror -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 \
 // RUN:         -triple i686--windows -Oz -emit-llvm %s -o - \
 // RUN:         | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-I386
-// RUN: %clang_cc1 -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 \
+// RUN: %clang_cc1 -Werror -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 \
 // RUN:         -triple x86_64--windows -Oz -emit-llvm %s -o - \
 // RUN:         | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-X64
 
+#include <intrin.h>
+
 #if defined(__i386__)
 char test__readfsbyte(unsigned long Offset) {
   return __readfsbyte(++Offset);