diff --git a/skimage/measure/_regionprops.py b/skimage/measure/_regionprops.py
index d285d453..72d1e2f4 100644
--- a/skimage/measure/_regionprops.py
+++ b/skimage/measure/_regionprops.py
@@ -440,18 +440,19 @@ def perimeter(image, neighbourhood=4):
         strel = STREL_4
     else:
         strel = STREL_8
-    eroded_image = ndimage.binary_erosion(image, strel)
+    eroded_image = ndimage.binary_erosion(image, strel, border_value=0)
     border_image = image - eroded_image
 
     # perimeter contribution: corresponding values in convolved image
     perimeter_weights = {
-        1:               (5, 7, 15, 17, 25, 27),
-        sqrt(2):         (21, 33),
-        1 + sqrt(2) / 2: (13, 23)
+        1:                 (5, 7, 15, 17, 25, 27),
+        sqrt(2):           (21, 33),
+        (1 + sqrt(2)) / 2: (13, 23)
     }
     perimeter_image = ndimage.convolve(border_image, np.array([[10, 2, 10],
                                                                [ 2, 1,  2],
-                                                               [10, 2, 10]]))
+                                                               [10, 2, 10]]),
+                                       mode='constant', cval=0)
     total_perimeter = 0
     for weight, values in perimeter_weights.items():
         num_values = 0
diff --git a/skimage/measure/tests/test_regionprops.py b/skimage/measure/tests/test_regionprops.py
index bd23d8b3..8185bf67 100644
--- a/skimage/measure/tests/test_regionprops.py
+++ b/skimage/measure/tests/test_regionprops.py
@@ -246,10 +246,10 @@ def test_orientation():
 
 def test_perimeter():
     per = regionprops(SAMPLE, ['Perimeter'])[0]['Perimeter']
-    assert_almost_equal(per, 59.2132034355964)
+    assert_almost_equal(per, 55.2487373415)
 
     per = perimeter(SAMPLE.astype('double'), neighbourhood=8)
-    assert_almost_equal(per, 43.1213203436)
+    assert_almost_equal(per, 46.8284271247)
 
 
 def test_solidity():