diff --git a/common/tokenize.gperf b/common/tokenize.gperf
index 913e3a735..2245ad540 100644
--- a/common/tokenize.gperf
+++ b/common/tokenize.gperf
@@ -13,7 +13,9 @@ center
 class
 client
 color
+Control
 coords
+Ctrl
 east
 fg
 flex
@@ -35,8 +37,14 @@ label
 layout
 left
 line
+Lock
 machine
 minimize
+Mod1
+Mod2
+Mod3
+Mod4
+Mod5
 mouse_enter
 mouse_leave
 mwfact
@@ -58,6 +66,7 @@ screen
 selected
 shadow
 shadow_offset
+Shift
 show_icons
 sizehints
 south
diff --git a/common/xutil.c b/common/xutil.c
index 22f4fcde1..8f262b4b3 100644
--- a/common/xutil.c
+++ b/common/xutil.c
@@ -333,39 +333,22 @@ xutil_error_init(const xcb_generic_error_t *e, xutil_error_t *err)
     return true;
 }
 
-/** Link a name to a key symbol */
-typedef struct
-{
-    const char *name;
-    xcb_keysym_t keysym;
-} keymod_t;
-
 xcb_keysym_t
-xutil_key_mask_fromstr(const char *keyname)
+xutil_key_mask_fromstr(const char *keyname, size_t len)
 {
-    /** List of keyname and corresponding X11 mask codes */
-    static const keymod_t KeyModList[] =
+    switch(a_tokenize(keyname, len))
     {
-        { "Shift", XCB_MOD_MASK_SHIFT },
-        { "Lock", XCB_MOD_MASK_LOCK },
-        { "Control", XCB_MOD_MASK_CONTROL },
-        { "Ctrl", XCB_MOD_MASK_CONTROL },
-        { "Mod1", XCB_MOD_MASK_1 },
-        { "Mod2", XCB_MOD_MASK_2 },
-        { "Mod3", XCB_MOD_MASK_3 },
-        { "Mod4", XCB_MOD_MASK_4 },
-        { "Mod5", XCB_MOD_MASK_5 },
-        { NULL, XCB_NO_SYMBOL }
-    };
-    int i;
-
-    if(keyname)
-        for(i = 0; KeyModList[i].name; i++)
-            if(!a_strcmp(keyname, KeyModList[i].name))
-                 return KeyModList[i].keysym;
-
-    return XCB_NO_SYMBOL;
-
+      case A_TK_SHIFT:   return XCB_MOD_MASK_SHIFT;
+      case A_TK_LOCK:    return XCB_MOD_MASK_LOCK;
+      case A_TK_CTRL:
+      case A_TK_CONTROL: return XCB_MOD_MASK_CONTROL;
+      case A_TK_MOD1:    return XCB_MOD_MASK_1;
+      case A_TK_MOD2:    return XCB_MOD_MASK_2;
+      case A_TK_MOD3:    return XCB_MOD_MASK_3;
+      case A_TK_MOD4:    return XCB_MOD_MASK_4;
+      case A_TK_MOD5:    return XCB_MOD_MASK_5;
+      default:           return XCB_NO_SYMBOL;
+    }
 }
 
 /** Permit to use mouse with many more buttons */
diff --git a/common/xutil.h b/common/xutil.h
index 46640e977..cec59aa37 100644
--- a/common/xutil.h
+++ b/common/xutil.h
@@ -112,7 +112,7 @@ typedef struct
 } xutil_error_t;
 
 bool xutil_error_init(const xcb_generic_error_t *, xutil_error_t *);
-xcb_keysym_t xutil_key_mask_fromstr(const char *);
+xcb_keysym_t xutil_key_mask_fromstr(const char *, size_t);
 unsigned int xutil_button_fromint(int);
 xcb_cursor_t xutil_cursor_new(xcb_connection_t *, unsigned int);
 
diff --git a/keybinding.c b/keybinding.c
index ec88a2b09..154f9371b 100644
--- a/keybinding.c
+++ b/keybinding.c
@@ -348,8 +348,10 @@ luaA_keybinding_new(lua_State *L)
     len = lua_objlen(L, 2);
     for(i = 1; i <= len; i++)
     {
+        size_t blen;
         lua_rawgeti(L, 2, i);
-        k->mod |= xutil_key_mask_fromstr(luaL_checkstring(L, -1));
+        key = luaL_checklstring(L, -1, &blen);
+        k->mod |= xutil_key_mask_fromstr(key, blen);
     }
 
     return luaA_keybinding_userdata_new(L, k);
diff --git a/mouse.c b/mouse.c
index 8a60e2d21..ccaa23ca2 100644
--- a/mouse.c
+++ b/mouse.c
@@ -1078,8 +1078,11 @@ luaA_button_new(lua_State *L)
     len = lua_objlen(L, 2);
     for(i = 1; i <= len; i++)
     {
+        size_t blen;
+        const char *buf;
         lua_rawgeti(L, 2, i);
-        button->mod |= xutil_key_mask_fromstr(luaL_checkstring(L, -1));
+        buf = luaL_checklstring(L, -1, &blen);
+        button->mod |= xutil_key_mask_fromstr(buf, blen);
     }
 
     return luaA_button_userdata_new(L, button);