diff --git a/include/X11/ImUtil.h b/include/X11/ImUtil.h
index ffdba1a939913bb50c2f589c99c015c89a3c936b..779e1dc156ec84a5405ca33c88a402d841896dda 100644
--- a/include/X11/ImUtil.h
+++ b/include/X11/ImUtil.h
@@ -15,16 +15,16 @@ _XGetBitsPerPixel(
 extern int
 _XSetImage(
     XImage *srcimg,
-    register XImage *dstimg,
-    register int x,
-    register int y);
+    XImage *dstimg,
+    int x,
+    int y);
 
 extern int
 _XReverse_Bytes(
-    register unsigned char *bpt,
-    register int nb);
+    unsigned char *bpt,
+    int nb);
 extern void
 _XInitImageFuncPtrs(
-    register XImage *image);
+    XImage *image);
 
 #endif /* _X11_IMUTIL_H_ */
diff --git a/include/X11/Xlibint.h b/include/X11/Xlibint.h
index 4214b235755576c8ba88069553b48fed6298a1fe..f28647452d7600fce7849d9988561eb8a18ea902 100644
--- a/include/X11/Xlibint.h
+++ b/include/X11/Xlibint.h
@@ -675,12 +675,12 @@ extern void _XFlushGCCache(Display *dpy, GC gc);
 #define Data32(dpy, data, len) _XData32(dpy, (_Xconst long *)data, len)
 extern int _XData32(
 	     Display *dpy,
-	     register _Xconst long *data,
+	     _Xconst long *data,
 	     unsigned len
 );
 extern void _XRead32(
 	     Display *dpy,
-	     register long *data,
+	     long *data,
 	     long len
 );
 #else
@@ -1382,10 +1382,10 @@ extern int _XF86LoadQueryLocaleFont(
 );
 
 extern void _XProcessWindowAttributes (
-    register Display *dpy,
+    Display *dpy,
     xChangeWindowAttributesReq *req,
-    register unsigned long valuemask,
-    register XSetWindowAttributes *attributes);
+    unsigned long valuemask,
+    XSetWindowAttributes *attributes);
 
 extern int _XDefaultError(
         Display *dpy,
@@ -1395,7 +1395,7 @@ extern int _XDefaultIOError(
         Display *dpy);
 
 extern void _XSetClipRectangles (
-    register Display *dpy,
+    Display *dpy,
     GC gc,
     int clip_x_origin, int clip_y_origin,
     XRectangle *rectangles,
@@ -1403,13 +1403,13 @@ extern void _XSetClipRectangles (
     int ordering);
 
 Status _XGetWindowAttributes(
-    register Display *dpy,
+    Display *dpy,
     Window w,
     XWindowAttributes *attr);
 
 int _XPutBackEvent (
-    register Display *dpy,
-    register XEvent *event);
+    Display *dpy,
+    XEvent *event);
 
 extern Bool _XIsEventCookie(
         Display *dpy,
diff --git a/src/GetWAttrs.c b/src/GetWAttrs.c
index 0f5f7bb89332495981e15583baca198b639e402f..0775eabc888774bf3ddf171305f24ecf4353c6d3 100644
--- a/src/GetWAttrs.c
+++ b/src/GetWAttrs.c
@@ -87,7 +87,7 @@ _XWAttrsHandler(
 
 Status
 _XGetWindowAttributes(
-    register Display *dpy,
+    Display *dpy,
     Window w,
     XWindowAttributes *attr)
 {
diff --git a/src/ImUtil.c b/src/ImUtil.c
index 0d996e8ec939e429b3282fc20efb1ce85bd591a9..36f08a033a30faf4a5d32040bd5c2361cebdf07c 100644
--- a/src/ImUtil.c
+++ b/src/ImUtil.c
@@ -269,7 +269,7 @@ static void _putbits(
  * valid, and reinit the functions if not.
  */
 void _XInitImageFuncPtrs (
-    register XImage *image)
+    XImage *image)
 {
 	image->f.create_image = XCreateImage;
 	image->f.destroy_image = _XDestroyImage;
@@ -918,9 +918,9 @@ static XImage *_XSubImage (
 
 int _XSetImage(
     XImage *srcimg,
-    register XImage *dstimg,
-    register int x,
-    register int y)
+    XImage *dstimg,
+    int x,
+    int y)
 {
 	register unsigned long pixel;
 	register int row, col;
diff --git a/src/PutBEvent.c b/src/PutBEvent.c
index 1768e032c329033d13e43d58c46433c188aa96d1..0f9df34290b2d2810b58234e054fb08944f4ba8e 100644
--- a/src/PutBEvent.c
+++ b/src/PutBEvent.c
@@ -34,8 +34,8 @@ from The Open Group.
 
 int
 _XPutBackEvent (
-    register Display *dpy,
-    register XEvent *event)
+    Display *dpy,
+    XEvent *event)
 	{
 	register _XQEvent *qelt;
 	XEvent store = *event;
diff --git a/src/PutImage.c b/src/PutImage.c
index 1954d0863abccc50c81f054f9f050d586a78789d..857ee916e920942447f65d33fc139038f0bc6553 100644
--- a/src/PutImage.c
+++ b/src/PutImage.c
@@ -119,8 +119,8 @@ static unsigned char const _reverse_nibs[0x100] = {
 
 int
 _XReverse_Bytes(
-    register unsigned char *bpt,
-    register int nb)
+    unsigned char *bpt,
+    int nb)
 {
     do {
 	*bpt = _reverse_byte[*bpt];
diff --git a/src/SetCRects.c b/src/SetCRects.c
index c7ad3fcf2f40cbee983995a377ec4c9a04192324..b18c449a6a0e23ad4638b78735e9cfd53ff6ff86 100644
--- a/src/SetCRects.c
+++ b/src/SetCRects.c
@@ -31,7 +31,7 @@ in this Software without prior written authorization from The Open Group.
 
 /* can only call when display is locked. */
 void _XSetClipRectangles (
-    register Display *dpy,
+    Display *dpy,
     GC gc,
     int clip_x_origin, int clip_y_origin,
     XRectangle *rectangles,
diff --git a/src/Window.c b/src/Window.c
index 85a28f372a548d08455b05c92266b350ec5fe6b9..e643f2197a0c059817e01d54052d8aac28467c7b 100644
--- a/src/Window.c
+++ b/src/Window.c
@@ -30,10 +30,10 @@ in this Software without prior written authorization from The Open Group.
 #include "Xlibint.h"
 
 void _XProcessWindowAttributes (
-    register Display *dpy,
+    Display *dpy,
     xChangeWindowAttributesReq *req,
-    register unsigned long valuemask,
-    register XSetWindowAttributes *attributes)
+    unsigned long valuemask,
+    XSetWindowAttributes *attributes)
 {
     unsigned long values[32];
     register unsigned long *value = values;
diff --git a/src/XlibInt.c b/src/XlibInt.c
index 3f97d72e2f0962bb4365a04b353915610e436f2d..6eb844e2eccd7a7a2f2fdb3936cf05fb27534006 100644
--- a/src/XlibInt.c
+++ b/src/XlibInt.c
@@ -269,7 +269,7 @@ void _XSetSeqSyncFunction(Display *dpy)
 #ifdef LONG64
 void _XRead32(
     Display *dpy,
-    register long *data,
+    long *data,
     long len)
 {
     register int *buf;
@@ -1648,7 +1648,7 @@ void Data(
 int
 _XData32(
     Display *dpy,
-    register _Xconst long *data,
+    _Xconst long *data,
     unsigned len)
 {
     register int *buf;