diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index c155c5f3ca..abedb4f948 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -419,7 +419,7 @@ s{PG_VERSION_STR "[^"]+"}{__STRINGIFY(x) #x\n#define __STRINGIFY2(z) __STRINGIFY
 		  || confess "Could not open ecpg_config.h";
 		print O <<EOF;
 #if (_MSC_VER > 1200)
-#define HAVE_LONG_LONG_INT_64
+#define HAVE_LONG_LONG_INT_64 1
 #define ENABLE_THREAD_SAFETY 1
 EOF
 		print O "#define USE_INTEGER_DATETIMES 1\n"