diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 01e5846b639..19a95ddc0e7 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -425,7 +425,7 @@ s{PG_VERSION_STR "[^"]+"}{PG_VERSION_STR "PostgreSQL $self->{strver}$extraver, c
 		  || 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 "#endif\n";