diff --git a/xf86drm.c b/xf86drm.c
index e67391b1..ac7af0d6 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -2743,6 +2743,24 @@ drm_public int drmDropMaster(int fd)
         return drmIoctl(fd, DRM_IOCTL_DROP_MASTER, NULL);
 }
 
+drm_public bool drmIsMaster(int fd)
+{
+        /* Detect master by attempting something that requires master.
+         *
+         * Authenticating magic tokens requires master and 0 is an
+         * internal kernel detail which we could use. Attempting this on
+         * a master fd would fail therefore fail with EINVAL because 0
+         * is invalid.
+         *
+         * A non-master fd will fail with EACCES, as the kernel checks
+         * for master before attempting to do anything else.
+         *
+         * Since we don't want to leak implementation details, use
+         * EACCES.
+         */
+        return drmAuthMagic(fd, 0) != -EACCES;
+}
+
 drm_public char *drmGetDeviceNameFromFd(int fd)
 {
     char name[128];
diff --git a/xf86drm.h b/xf86drm.h
index 7773d71a..9e920db9 100644
--- a/xf86drm.h
+++ b/xf86drm.h
@@ -37,6 +37,7 @@
 #include <stdarg.h>
 #include <sys/types.h>
 #include <stdint.h>
+#include <stdbool.h>
 #include <drm.h>
 
 #if defined(__cplusplus)
@@ -733,6 +734,7 @@ extern void drmMsg(const char *format, ...) DRM_PRINTFLIKE(1, 2);
 
 extern int drmSetMaster(int fd);
 extern int drmDropMaster(int fd);
+extern bool drmIsMaster(int fd);
 
 #define DRM_EVENT_CONTEXT_VERSION 4