diff --git a/qemu-keymap.c b/qemu-keymap.c
index 229866e004..8c80f7a4ed 100644
--- a/qemu-keymap.c
+++ b/qemu-keymap.c
@@ -140,6 +140,18 @@ static void usage(FILE *out)
             names.options ?: "-");
 }
 
+static xkb_mod_mask_t get_mod(struct xkb_keymap *map, const char *name)
+{
+    xkb_mod_index_t mod;
+    xkb_mod_mask_t mask = 0;
+
+    mod = xkb_keymap_mod_get_index(map, name);
+    if (mod != XKB_MOD_INVALID) {
+        mask = (1 << mod);
+    }
+    return mask;
+}
+
 int main(int argc, char *argv[])
 {
     struct xkb_context *ctx;
@@ -215,14 +227,10 @@ int main(int argc, char *argv[])
                 mod, xkb_keymap_mod_get_name(map, mod));
     }
 
-    mod = xkb_keymap_mod_get_index(map, "Shift");
-    shift = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "Control");
-    ctrl = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "AltGr");
-    altgr = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "NumLock");
-    numlock = (1 << mod);
+    shift = get_mod(map, "Shift");
+    ctrl = get_mod(map, "Control");
+    altgr = get_mod(map, "AltGr");
+    numlock = get_mod(map, "NumLock");
 
     state = xkb_state_new(map);
     xkb_keymap_key_for_each(map, walk_map, state);