diff --git a/nac3standalone/demo/classes.py b/nac3standalone/demo/classes.py
index ba489b48..14df8f2f 100644
--- a/nac3standalone/demo/classes.py
+++ b/nac3standalone/demo/classes.py
@@ -2,6 +2,10 @@
 def output_int(x: int32):
     ...
 
+@extern
+def output_long(x: int64):
+    ...
+
 
 class A:
     a: int32
diff --git a/nac3standalone/demo/demo.c b/nac3standalone/demo/demo.c
index fb9dbd1f..90e4c05b 100644
--- a/nac3standalone/demo/demo.c
+++ b/nac3standalone/demo/demo.c
@@ -5,6 +5,10 @@ void output_int(int x) {
     printf("%d\n", x);
 }
 
+void output_long(long x) {
+    printf("%ld\n", x);
+}
+
 void output_asciiart(int x) {
     static char chars[] = " .,-:;i+hHM$*#@  ";
     if(x < 0) {