diff --git a/PyInstaller/hooks/hook-matplotlib.py b/PyInstaller/hooks/hook-matplotlib.py
index 9e4f92ba9c3..10667dc75a0 100644
--- a/PyInstaller/hooks/hook-matplotlib.py
+++ b/PyInstaller/hooks/hook-matplotlib.py
@@ -14,6 +14,7 @@
 
 mpl_data_dir = exec_statement(
     "import matplotlib; print(matplotlib.get_data_path())")
+assert mpl_data_dir, "Failed to determine matplotlib's data directory!"
 
 datas = [
     (mpl_data_dir, "matplotlib/mpl-data"),