diff --git a/src/s_sound.c b/src/s_sound.c
index d108363eb..5ed9fd83a 100644
--- a/src/s_sound.c
+++ b/src/s_sound.c
@@ -134,6 +134,7 @@ consvar_t cv_playmusicifunfocused = {"playmusicifunfocused", "No", CV_SAVE, CV_Y
 consvar_t cv_playsoundsifunfocused = {"playsoundsifunfocused", "No", CV_SAVE, CV_YesNo, NULL, 0, NULL, NULL, 0, 0, NULL};
 
 #ifdef HAVE_OPENMPT
+openmpt_module *openmpt_mhandle = NULL;
 static CV_PossibleValue_t interpolationfilter_cons_t[] = {{0, "Default"}, {1, "None"}, {2, "Linear"}, {4, "Cubic"}, {8, "Windowed sinc"}, {0, NULL}};
 consvar_t cv_modfilter = {"modfilter", "0", CV_SAVE|CV_CALL, interpolationfilter_cons_t, ModFilter_OnChange, 0, NULL, NULL, 0, 0, NULL};
 #endif
@@ -1910,6 +1911,10 @@ UINT32 S_GetMusicPosition(void)
 /// In this section: mazmazz doesn't know how to do dynamic arrays or struct pointers!
 /// ------------------------
 
+char music_stack_nextmusname[7];
+boolean music_stack_noposition = false;
+UINT32 music_stack_fadeout = 0;
+UINT32 music_stack_fadein = 0;
 static musicstack_t *music_stacks = NULL;
 static musicstack_t *last_music_stack = NULL;
 
diff --git a/src/s_sound.h b/src/s_sound.h
index 119722af4..3334fcb69 100644
--- a/src/s_sound.h
+++ b/src/s_sound.h
@@ -22,7 +22,7 @@
 
 #ifdef HAVE_OPENMPT
 #include "libopenmpt/libopenmpt.h"
-openmpt_module *openmpt_mhandle;
+extern openmpt_module *openmpt_mhandle;
 #endif
 
 // mask used to indicate sound origin is player item pickup
@@ -262,10 +262,10 @@ typedef struct musicstack_s
     struct musicstack_s *next;
 } musicstack_t;
 
-char music_stack_nextmusname[7];
-boolean music_stack_noposition;
-UINT32 music_stack_fadeout;
-UINT32 music_stack_fadein;
+extern char music_stack_nextmusname[7];
+extern boolean music_stack_noposition;
+extern UINT32 music_stack_fadeout;
+extern UINT32 music_stack_fadein;
 
 void S_SetStackAdjustmentStart(void);
 void S_AdjustMusicStackTics(void);
@@ -333,7 +333,7 @@ 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