diff --git a/test cases/python/4 custom target depends extmodule/blaster.py b/test cases/python/4 custom target depends extmodule/blaster.py
index 61b11f922977..65b6493df890 100644
--- a/test cases/python/4 custom target depends extmodule/blaster.py	
+++ b/test cases/python/4 custom target depends extmodule/blaster.py	
@@ -10,6 +10,9 @@
 if list(filedir.glob('ext/*tachyon*')):
     sys.path.insert(0, (filedir / 'ext').as_posix())
 
+if hasattr(os, 'add_dll_directory'):
+    os.add_dll_directory(filedir / 'ext' / 'lib')
+
 import tachyon
 
 parser = argparse.ArgumentParser()
diff --git a/test cases/python3/4 custom target depends extmodule/blaster.py b/test cases/python3/4 custom target depends extmodule/blaster.py
index d2c93ad038fa..9cce64505e5d 100644
--- a/test cases/python3/4 custom target depends extmodule/blaster.py	
+++ b/test cases/python3/4 custom target depends extmodule/blaster.py	
@@ -10,6 +10,9 @@
 if list(filedir.glob('ext/*tachyon.*')):
     sys.path.insert(0, (filedir / 'ext').as_posix())
 
+if hasattr(os, 'add_dll_directory'):
+    os.add_dll_directory(filedir / 'ext' / 'lib')
+
 import tachyon
 
 parser = argparse.ArgumentParser()