diff --git a/src/pytorch_lightning/tuner/lr_finder.py b/src/pytorch_lightning/tuner/lr_finder.py
index 9e584708f369e..71d96ef428f35 100644
--- a/src/pytorch_lightning/tuner/lr_finder.py
+++ b/src/pytorch_lightning/tuner/lr_finder.py
@@ -39,7 +39,7 @@
 else:
     from tqdm import tqdm
 
-_MATPLOTLIB_AVAILABLE: bool = _RequirementAvailable("matplotlib")  # type: ignore[assignment]
+_MATPLOTLIB_AVAILABLE = _RequirementAvailable("matplotlib")
 if _MATPLOTLIB_AVAILABLE and TYPE_CHECKING:
     import matplotlib.pyplot as plt