diff --git a/configure.ac b/configure.ac
index c16684159..2c70cda30 100644
--- a/configure.ac
+++ b/configure.ac
@@ -218,7 +218,8 @@ AC_SUBST(DLOPEN_LIBS)
 dnl Checks for library functions.
 AC_CHECK_FUNCS([backtrace ffs geteuid getuid issetugid getresuid \
 	getdtablesize getifaddrs getpeereid getpeerucred getprogname getzoneid \
-	mmap seteuid shmctl64 strncasecmp vasprintf vsnprintf walkcontext setitimer])
+	mmap posix_fallocate seteuid shmctl64 strncasecmp vasprintf vsnprintf \
+	walkcontext setitimer])
 AC_REPLACE_FUNCS([reallocarray strcasecmp strcasestr strlcat strlcpy strndup])
 
 AC_CHECK_DECLS([program_invocation_short_name], [], [], [[#include <errno.h>]])
diff --git a/hw/xwayland/xwayland-shm.c b/hw/xwayland/xwayland-shm.c
index 1beade9c9..e8545b3be 100644
--- a/hw/xwayland/xwayland-shm.c
+++ b/hw/xwayland/xwayland-shm.c
@@ -24,6 +24,10 @@
  * SOFTWARE.
  */
 
+#ifdef HAVE_CONFIG_H
+#include <dix-config.h>
+#endif
+
 #include "xwayland.h"
 
 #include <sys/mman.h>
diff --git a/include/dix-config.h.in b/include/dix-config.h.in
index 940d2b7e2..a164c15b5 100644
--- a/include/dix-config.h.in
+++ b/include/dix-config.h.in
@@ -521,4 +521,7 @@
 /* Have setitimer support */
 #undef HAVE_SETITIMER
 
+/* Have posix_fallocate() */
+#undef HAVE_POSIX_FALLOCATE
+
 #endif /* _DIX_CONFIG_H_ */