diff --git a/tools/msvs/msi/custom_actions.c b/tools/msvs/msi/custom_actions.cc
similarity index 83%
rename from tools/msvs/msi/custom_actions.c
rename to tools/msvs/msi/custom_actions.cc
index 5e7d617f387..9a23d557476 100644
--- a/tools/msvs/msi/custom_actions.c
+++ b/tools/msvs/msi/custom_actions.cc
@@ -6,7 +6,7 @@
 #include <wcautil.h>
 
 
-UINT WINAPI BroadcastEnvironmentUpdate(MSIHANDLE hInstall) {
+extern "C" UINT WINAPI BroadcastEnvironmentUpdate(MSIHANDLE hInstall) {
   HRESULT hr = S_OK;
   UINT er = ERROR_SUCCESS;
 
@@ -27,7 +27,7 @@ UINT WINAPI BroadcastEnvironmentUpdate(MSIHANDLE hInstall) {
 }
 
 
-BOOL WINAPI DllMain(HINSTANCE hInst, ULONG ulReason, VOID* dummy) {
+extern "C" BOOL WINAPI DllMain(HINSTANCE hInst, ULONG ulReason, VOID* dummy) {
   switch (ulReason) {
     case DLL_PROCESS_ATTACH:
       WcaGlobalInitialize(hInst);
diff --git a/tools/msvs/msi/custom_actions.vcxproj b/tools/msvs/msi/custom_actions.vcxproj
index ae82905cd4b..3716f07ff6d 100644
--- a/tools/msvs/msi/custom_actions.vcxproj
+++ b/tools/msvs/msi/custom_actions.vcxproj
@@ -169,7 +169,7 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
-    <ClCompile Include="custom_actions.c">
+    <ClCompile Include="custom_actions.cc">
     </ClCompile>
   </ItemGroup>
   <ItemGroup>