diff --git a/src/tools/msvc/Project.pm b/src/tools/msvc/Project.pm
index 47ec46fbde..e64b6a6a3a 100644
--- a/src/tools/msvc/Project.pm
+++ b/src/tools/msvc/Project.pm
@@ -107,6 +107,7 @@ sub AddIncludeDir {
 sub AddDefine {
 	my ($self, $def) = @_;
 
+	$def =~ s/"/""/g;
 	$self->{defines} .= $def . ';';
 }