diff --git a/src/byteswap.c b/src/byteswap.c
index 66b0d4d..5d59546 100644
--- a/src/byteswap.c
+++ b/src/byteswap.c
@@ -77,7 +77,7 @@ void word_swap_page(unsigned short *page, int longwordcount) {
 /*                                                              */
 /****************************************************************/
 
-unsigned char reversedbits[256] = {
+const unsigned char reversedbits[256] = {
     /* table of bytes with their bits reversed */
     0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
 
diff --git a/src/initdsp.c b/src/initdsp.c
index ada7a32..8018f1b 100644
--- a/src/initdsp.c
+++ b/src/initdsp.c
@@ -708,7 +708,6 @@ void flush_display_region(int x, int y, int w, int h)
 #ifdef BYTESWAP
 void byte_swapped_displayregion(int x, int y, int w, int h)
 {
-  extern unsigned char reversedbits[];
   register unsigned int *longptr;
 
   /* Get QUAD byte aligned pointer */
diff --git a/src/mnxmeth.c b/src/mnxmeth.c
index 553018c..23deb80 100644
--- a/src/mnxmeth.c
+++ b/src/mnxmeth.c
@@ -64,6 +64,8 @@ extern DLword ERASE_atom;
 extern DLword PAINT_atom;
 extern DLword REPLACE_atom;
 
+extern const unsigned char reversedbits[];
+
 /**************************************************************/
 /* Xerrhandler.                                               */
 /* Utility function to make URaid the error handler for X.    */
@@ -2529,7 +2531,6 @@ MNXGrabPointer(LispArgs args)
   Pixmap bits;
   Window promptw;
   int res, i;
-  extern unsigned char reversedbits[];
   unsigned char *src;
   unsigned char srcbits[32]; /* holds the reversed bits for cursor */
 
@@ -2738,7 +2739,6 @@ MNXSetCursor(LispArgs args) /* args[0] = Medley screen */
   Cursor new_cursor;
   Window win;
   unsigned char srcbits[32]; /* hold the reversed-bits for cursor */
-  extern unsigned char reversedbits[];
   unsigned char *src;
   int i;
 
diff --git a/src/xcursor.c b/src/xcursor.c
index 3ba9b8b..f366fba 100644
--- a/src/xcursor.c
+++ b/src/xcursor.c
@@ -193,7 +193,7 @@ void init_Xcursor(Display *display, Window window)
 
 void set_Xcursor(DspInterface dsp, const uint8_t *bitmap, int hotspot_x, int hotspot_y, Cursor *return_cursor, int from_lisp)
 {
-  extern unsigned char reversedbits[];
+  extern const unsigned char reversedbits[];
   unsigned char image[32];
   int i;
   Pixmap Cursor_src, Cursor_msk;