diff --git a/visualc/VS2010/mbedTLS.vcxproj b/visualc/VS2010/mbedTLS.vcxproj
index c75b35354..e36a7b570 100644
--- a/visualc/VS2010/mbedTLS.vcxproj
+++ b/visualc/VS2010/mbedTLS.vcxproj
@@ -258,6 +258,7 @@
     <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" />