diff --git a/setup.go b/setup.go
index 14e1e69..51554f3 100644
--- a/setup.go
+++ b/setup.go
@@ -136,7 +136,7 @@ func (a *Apple2) SetForceCaps(value bool) {
 }
 
 func (a *Apple2) loadRom(filename string) error {
-	if a.board == "base64a" && isInternalResource(filename) {
+	if a.board == "base64a" && filename == "<custom>" {
 		// The ROM of the base64a has several file and pages
 		loadBase64aRom(a)
 		return nil