diff --git a/src/traccuracy/matchers/_ctc.py b/src/traccuracy/matchers/_ctc.py
index 25827ff2..23f02be8 100644
--- a/src/traccuracy/matchers/_ctc.py
+++ b/src/traccuracy/matchers/_ctc.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 import networkx as nx
@@ -24,7 +26,7 @@ class CTCMatcher(Matcher):
     for complete details.
     """
 
-    def _compute_mapping(self, gt_graph: "TrackingGraph", pred_graph: "TrackingGraph"):
+    def _compute_mapping(self, gt_graph: TrackingGraph, pred_graph: TrackingGraph):
         """Run ctc matching
 
         Args:
diff --git a/src/traccuracy/matchers/_iou.py b/src/traccuracy/matchers/_iou.py
index 189c4e6d..7a48fbc4 100644
--- a/src/traccuracy/matchers/_iou.py
+++ b/src/traccuracy/matchers/_iou.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import numpy as np
 from tqdm import tqdm
 
@@ -110,7 +112,7 @@ class IOUMatcher(Matcher):
     def __init__(self, iou_threshold=0.6):
         self.iou_threshold = iou_threshold
 
-    def _compute_mapping(self, gt_graph: "TrackingGraph", pred_graph: "TrackingGraph"):
+    def _compute_mapping(self, gt_graph: TrackingGraph, pred_graph: TrackingGraph):
         """Computes IOU mapping for a set of grpahs
 
         Args: