diff --git a/os/WaitFor.c b/os/WaitFor.c
index 613608faf..fa6a99b18 100644
--- a/os/WaitFor.c
+++ b/os/WaitFor.c
@@ -90,24 +90,6 @@ SOFTWARE.
 #define GetErrno() errno
 #endif
 
-/* like ffs, but uses fd_mask instead of int as argument, so it works
-   when fd_mask is longer than an int, such as common 64-bit platforms */
-/* modifications by raphael */
-int
-mffs(fd_mask mask)
-{
-    int i;
-
-    if (!mask)
-        return 0;
-    i = 1;
-    while (!(mask & 1)) {
-        i++;
-        mask >>= 1;
-    }
-    return i;
-}
-
 #ifdef DPMSExtension
 #include <X11/extensions/dpmsconst.h>
 #endif
diff --git a/os/osdep.h b/os/osdep.h
index 3ab81958c..67958fd77 100644
--- a/os/osdep.h
+++ b/os/osdep.h
@@ -148,13 +148,6 @@ extern Bool NewOutputPending;
 
 extern WorkQueuePtr workQueue;
 
-/* in WaitFor.c */
-#if defined(WIN32) && !defined(__CYGWIN__)
-typedef long int fd_mask;
-#endif
-#define ffs mffs
-extern int mffs(fd_mask);
-
 /* in access.c */
 extern Bool ComputeLocalClient(ClientPtr client);