diff --git a/pl/rules.pl b/pl/rules.pl
index 53264a0..90778b9 100644
--- a/pl/rules.pl
+++ b/pl/rules.pl
@@ -6,7 +6,7 @@ my $gl_libs = "";
 if (param_get("classic-theme")) {
     add_cflags("-DUSE_CLASSIC_THEME");
 }
-if (grep(@backends, /^x11$/)) {
+if (grep(/^x11$/, @backends)) {
     add_cflags("-DUSE_X11");
     new_object("src/backend/x11.c");
     add_libs("-lX11");
@@ -19,7 +19,7 @@ if (grep(@backends, /^x11$/)) {
     }
 }
 
-if (grep(@backends, /^gdi$/)) {
+if (grep(/^gdi$/, @backends)) {
     add_cflags("-DUSE_GDI");
     new_object("src/backend/gdi.c");
     add_libs("-lgdi32");