diff --git a/skimage/color/colorlabel.py b/skimage/color/colorlabel.py
index 222c50c8..ed74f3a8 100644
--- a/skimage/color/colorlabel.py
+++ b/skimage/color/colorlabel.py
@@ -112,7 +112,7 @@ def label2rgb(label, image=None, colors=None, alpha=0.3,
         label = label - offset  # Make sure you don't modify the input array.
         bg_label -= offset
 
-    new_type = np.min_scalar_type(label.max())
+    new_type = np.min_scalar_type(int(label.max()))
     if new_type == np.bool:
         new_type = np.uint8
     label = label.astype(new_type)
diff --git a/skimage/segmentation/_join.py b/skimage/segmentation/_join.py
index d7988742..892b85e2 100644
--- a/skimage/segmentation/_join.py
+++ b/skimage/segmentation/_join.py
@@ -114,11 +114,12 @@ def relabel_sequential(label_field, offset=1):
     >>> relab
     array([5, 5, 6, 6, 7, 9, 8])
     """
+    m = label_field.max()
     if not np.issubdtype(label_field.dtype, np.int):
-        label_field = label_field.astype(np.int)
+        new_type = np.min_scalar_type(int(m))
+        label_field = label_field.astype(new_type)
     labels = np.unique(label_field)
     labels0 = labels[labels != 0]
-    m = labels.max()
     if m == len(labels0):  # nothing to do, already 1...n labels
         return label_field, labels, labels
     forward_map = np.zeros(m+1, int)