diff --git a/pesto/utils/hcqt.py b/pesto/utils/hcqt.py
index 4c92564ce46c05002f0d7c9ffca548818b7db0ca..f7ff5610feb4b3c8d3bb29affc9a4ea5d2661538 100644
--- a/pesto/utils/hcqt.py
+++ b/pesto/utils/hcqt.py
@@ -364,7 +364,7 @@ class HarmonicCQT(nn.Module):
             sr: int = 22050,
             hop_length: int = 512,
             fmin: float = 32.7,
-            fmax: float | None = None,
+            fmax: Optional[float] = None,
             bins_per_semitone: int = 1,
             n_bins: int = 84,
             center_bins: bool = True