diff --git a/include/grpc/support/port_platform.h b/include/grpc/support/port_platform.h
index 57fed18cf68..d257164547a 100644
--- a/include/grpc/support/port_platform.h
+++ b/include/grpc/support/port_platform.h
@@ -46,10 +46,11 @@
 #define NOMINMAX
 #endif /* NOMINMAX */
 
-#if defined(_WIN32_WINNT)
-#if _WIN32_WINNT < 0x0600
-#undef _WIN32_WINNT
-#define _WIN32_WINNT 0x0600
+#ifndef _WIN32_WINNT
+#error "Please compile grpc with _WIN32_WINNT of at least 0x600 (aka Windows Vista)"
+#else /* !defined(_WIN32_WINNT) */
+#if (_WIN32_WINNT < 0x0600)
+#error "Please compile grpc with _WIN32_WINNT of at least 0x600 (aka Windows Vista)"
 #endif /* _WIN32_WINNT < 0x0600 */
 #endif /* defined(_WIN32_WINNT) */
 
diff --git a/vsprojects/global.props b/vsprojects/global.props
index 6858bd7b9d4..4647436e9e6 100644
--- a/vsprojects/global.props
+++ b/vsprojects/global.props
@@ -6,7 +6,7 @@
   <ItemDefinitionGroup>
     <ClCompile>
       <AdditionalIncludeDirectories>$(ProjectDir)\..\..;$(ProjectDir)\..\..\include;$(ProjectDir)\..\..\third_party\protobuf\src;$(ProjectDir)\..\packages\grpc.dependencies.openssl.1.0.2.2\build\native\include;$(ProjectDir)\..\..\third_party\gflags\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>_SCL_SECURE_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_UNICODE;UNICODE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_WIN32_WINNT=0x600;_SCL_SECURE_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_UNICODE;UNICODE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <WarningLevel>EnableAllWarnings</WarningLevel>
     </ClCompile>
   </ItemDefinitionGroup>