diff --git a/win_build/boinc_os_ss.vcxproj b/win_build/boinc_os_ss.vcxproj
index 7531d3900f..3060b886e3 100644
--- a/win_build/boinc_os_ss.vcxproj
+++ b/win_build/boinc_os_ss.vcxproj
@@ -363,7 +363,7 @@
     <ClCompile Include="..\lib\gui_rpc_client.cpp" />
     <ClCompile Include="..\lib\gui_rpc_client_ops.cpp" />
     <ClCompile Include="..\lib\hostinfo.cpp" />
-    <ClCompile Include="..\lib\md5.c" />
+    <ClCompile Include="..\lib\md5.cpp" />
     <ClCompile Include="..\lib\md5_file.cpp" />
     <ClCompile Include="..\lib\mfile.cpp" />
     <ClCompile Include="..\lib\miofile.cpp" />
diff --git a/win_build/boincmgr.vcxproj b/win_build/boincmgr.vcxproj
index 101e39014e..5457be75c7 100644
--- a/win_build/boincmgr.vcxproj
+++ b/win_build/boincmgr.vcxproj
@@ -321,10 +321,7 @@
     <ClCompile Include="..\lib\filesys.cpp" />
     <ClCompile Include="..\lib\hostinfo.cpp" />
     <ClCompile Include="..\lib\idlemon_win.cpp" />
-    <ClCompile Include="..\lib\md5.c">
-      <CompileAs Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">CompileAsCpp</CompileAs>
-      <CompileAs Condition="'$(Configuration)|$(Platform)'=='Release|x64'">CompileAsCpp</CompileAs>
-    </ClCompile>
+    <ClCompile Include="..\lib\md5.cpp" />
     <ClCompile Include="..\lib\md5_file.cpp" />
     <ClCompile Include="..\lib\mfile.cpp" />
     <ClCompile Include="..\lib\miofile.cpp" />