diff --git a/pyebsdindex/__init__.py b/pyebsdindex/__init__.py
index 628013e..1f0768e 100644
--- a/pyebsdindex/__init__.py
+++ b/pyebsdindex/__init__.py
@@ -21,7 +21,7 @@
         if len(gpu) > 0:
             _pyopencl_installed = True
     except:
-        raise ImportError
+        raise ImportError()
 except ImportError:
     _pyopencl_installed = False