diff --git a/imagelib/common.py b/imagelib/common.py
index fc723f1..229387f 100644
--- a/imagelib/common.py
+++ b/imagelib/common.py
@@ -1,3 +1,5 @@
+import numpy as np
+
 def normalize_channels(img, target_channels):
     img_shape_len = len(img.shape)
     if img_shape_len == 2: