diff --git a/visualc/vngspice.vcproj b/visualc/vngspice.vcproj
index 96521aa48..788b32c30 100644
--- a/visualc/vngspice.vcproj
+++ b/visualc/vngspice.vcproj
@@ -510,7 +510,7 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories=""$(ProjectDir)..\src\maths\poly";"$(ProjectDir)..\src\frontend";"$(ProjectDir)..\src\spicelib\devices";"$(ProjectDir)..\src\include";"$(ProjectDir)include""
-				PreprocessorDefinitions="_CRT_SECURE_NO_DEPRECATE;SIMULATOR;NGDEBUG;CONSOLE"
+				PreprocessorDefinitions="_CRT_SECURE_NO_DEPRECATE;SIMULATOR;NGDEBUG;CONSOLE;CONFIG64"
 				MinimalRebuild="true"
 				ExceptionHandling="0"
 				BasicRuntimeChecks="0"