diff --git a/kitty/cli.py b/kitty/cli.py
index fb6b27e76..87ba27730 100644
--- a/kitty/cli.py
+++ b/kitty/cli.py
@@ -36,9 +36,9 @@ class CompletionRelativeTo(Enum):
 class CompletionSpec:
 
     type: CompletionType = CompletionType.none
-    kwds: Sequence[str] = ()
-    extensions: Sequence[str] = ()
-    mime_patterns: Sequence[str] = ()
+    kwds: Tuple[str,...] = ()
+    extensions: Tuple[str,...] = ()
+    mime_patterns: Tuple[str,...] = ()
     group: str = ''
     relative_to: CompletionRelativeTo = CompletionRelativeTo.cwd
 
@@ -50,13 +50,13 @@ class CompletionSpec:
             if ck == 'type':
                 self.type = getattr(CompletionType, vv)
             elif ck == 'kwds':
-                self.kwds = tuple(vv.split(','))
+                self.kwds += tuple(vv.split(','))
             elif ck == 'ext':
-                self.extensions = tuple(vv.split(','))
+                self.extensions += tuple(vv.split(','))
             elif ck == 'group':
                 self.group = vv
             elif ck == 'mime':
-                self.mime_patterns = tuple(vv.split(','))
+                self.mime_patterns += tuple(vv.split(','))
             elif ck == 'relative':
                 if vv == 'conf':
                     self.relative_to = CompletionRelativeTo.config_dir