diff --git a/src/s_sound.h b/src/s_sound.h
index 2a904faf..eeb1f0ab 100644
--- a/src/s_sound.h
+++ b/src/s_sound.h
@@ -236,7 +236,7 @@ void S_StopSoundByNum(sfxenum_t sfxnum);
 #ifdef MUSICSLOT_COMPATIBILITY
 // For compatibility with code/scripts relying on older versions
 // This is a list of all the "special" slot names and their associated numbers
-const char *compat_special_music_slots[16];
+extern const char *compat_special_music_slots[16];
 #endif
 
 #endif