--- a/hcalc.h
+++ b/hcalc.h
@@ -25,8 +25,8 @@
 extern Pixmap face;
 extern Pixmap chars;
 
-int bit_on;
-int bit_off;
+extern int bit_on;
+extern int bit_off;
 
 extern int char_to_x[256];
 extern char charmap[];