diff --git a/setup.py b/setup.py
index 591cf179d..3c989b238 100644
--- a/setup.py
+++ b/setup.py
@@ -231,9 +231,9 @@ class pil_build_ext(build_ext):
 
         if _find_library_file(self, "tiff"):
             feature.tiff = "tiff"
-        if sys.platform == "win32" and find_library_file(self, "libtiff"):
+        if sys.platform == "win32" and _find_library_file(self, "libtiff"):
             feature.tiff = "libtiff"
-        if sys.platform == "darwin" and find_library_file(self, "libtiff"):
+        if sys.platform == "darwin" and _find_library_file(self, "libtiff"):
             feature.tiff = "libtiff"
 
         if _find_library_file(self, "freetype"):