diff --git a/visualc/VS2010/mbedTLS.vcxproj b/visualc/VS2010/mbedTLS.vcxproj
index 1ffc1f6e05..18b613ee02 100644
--- a/visualc/VS2010/mbedTLS.vcxproj
+++ b/visualc/VS2010/mbedTLS.vcxproj
@@ -260,6 +260,7 @@
     <ClInclude Include="..\..\tests\include\test\drivers\signature.h" />
     <ClInclude Include="..\..\tests\include\test\drivers\size.h" />
     <ClInclude Include="..\..\tests\include\test\drivers\test_driver.h" />
+    <ClInclude Include="..\..\library\bignum_internal.h" />
     <ClInclude Include="..\..\library\check_crypto_config.h" />
     <ClInclude Include="..\..\library\common.h" />
     <ClInclude Include="..\..\library\constant_time_internal.h" />