diff --git a/xkb/xkbUtils.c b/xkb/xkbUtils.c
index 9ffc4553cb..1045d98b38 100644
--- a/xkb/xkbUtils.c
+++ b/xkb/xkbUtils.c
@@ -665,6 +665,13 @@ XkbAdjustGroup(int group, XkbControlsPtr ctrls)
 {
     unsigned act;
 
+    /* A keymap with no groups leaves nothing to adjust into, and every action
+     * below misbehaves: wrapping divides by zero, clamping underflows to -1,
+     * and the negative-group loop never terminates.
+     */
+    if (ctrls->num_groups == 0)
+        return XkbGroup1Index;
+
     act = XkbOutOfRangeGroupAction(ctrls->groups_wrap);
     if (group < 0) {
         while (group < 0) {