matplotlib
diff --git a/‎setupext.py
Copy file name to clipboardExpand all lines: setupext.py
+5-2Lines changed: 5 additions & 2 deletions b/‎setupext.py
Copy file name to clipboardExpand all lines: setupext.py
+5-2Lines changed: 5 additions & 2 deletions
@@ -1014,8 +1014,11 @@ def check(self):
                 'libpng', 'png.h',
                 min_version='1.2', version=version)
         except CheckFailed as e:
-            self.__class__.found_external = False
-            return str(e) + ' Using unknown version.'
+            include_dirs = [
+                os.path.join(dir, 'include') for dir in get_base_dirs()]
+            if has_include_file(include_dirs, 'png.h'):
+                return str(e) + ' Using unknown version found on system.'
+            raise
 
     def get_extension(self):
         sources = [