diff --git a/kitty/key_encoding.c b/kitty/key_encoding.c
index e7f10719e..51df52c2e 100644
--- a/kitty/key_encoding.c
+++ b/kitty/key_encoding.c
@@ -296,10 +296,10 @@ ctrled_key(const char key) { // {{{
 
 static int
 encode_printable_ascii_key_legacy(const KeyEvent *ev, char *output) {
-    if (!ev->mods.value) return snprintf(output, KEY_BUFFER_SIZE, "%c", (char)ev->key);
+    unsigned mods = ev->mods.value & ~(GLFW_MOD_NUM_LOCK | GLFW_MOD_CAPS_LOCK);
+    if (!mods) return snprintf(output, KEY_BUFFER_SIZE, "%c", (char)ev->key);
 
     char key = ev->key;
-    unsigned mods = ev->mods.value;
     if (mods & SHIFT) {
         const char shifted = ev->shifted_key;
         if (shifted && shifted != key && (!(mods & CTRL) || key < 'a' || key > 'z')) {
diff --git a/kitty_tests/keys.py b/kitty_tests/keys.py
index 190e7949c..a08dadfb6 100644
--- a/kitty_tests/keys.py
+++ b/kitty_tests/keys.py
@@ -18,6 +18,7 @@ class TestKeys(BaseTest):
         enc = defines.encode_key_for_tty
         ae = self.assertEqual
         shift, alt, ctrl, super, hyper, meta = defines.GLFW_MOD_SHIFT, defines.GLFW_MOD_ALT, defines.GLFW_MOD_CONTROL, defines.GLFW_MOD_SUPER, defines.GLFW_MOD_HYPER, defines.GLFW_MOD_META  # noqa
+        num_lock, caps_lock = defines.GLFW_MOD_NUM_LOCK, defines.GLFW_MOD_CAPS_LOCK
         press, repeat, release = defines.GLFW_PRESS, defines.GLFW_REPEAT, defines.GLFW_RELEASE  # noqa
 
         def csi(mods=0, num=1, action=1, shifted_key=0, alternate_key=0, text=None, trailer='u'):
@@ -398,6 +399,7 @@ class TestKeys(BaseTest):
         for key in '~!@#$%^&*()_+{}|:"<>?':
             ae(enc(key=ord(key), mods=alt), '\x1b' + key)
         ae(enc(key=ord(' ')), ' ')
+        ae(enc(key=ord(' '), mods=ctrl | num_lock | caps_lock), '\0')
         ae(enc(key=ord(' '), mods=ctrl), '\0')
         ae(enc(key=ord(' '), mods=alt), '\x1b ')
         ae(enc(key=ord(' '), mods=shift), ' ')