diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86f7271..19ec298 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ Version 0.1.35
 - #374 Support pyzbar
 - #372 Support pydmtxlib
 - #371 Ugly error message when opening file with non-ascii characters in name
+- #370 OpenCV Error when subsegmenting
 - #369 Keyboard shortcuts box too tall on some displays
 - #368 Ugly error message when creating a new inselect document on Mac OS X
 - #367 Reveal file doesn't work on Windows
diff --git a/inselect/lib/segment.py b/inselect/lib/segment.py
index 4f36fac..6423464 100644
--- a/inselect/lib/segment.py
+++ b/inselect/lib/segment.py
@@ -369,15 +369,19 @@ def segment_grabcut(image, window=None, seeds=[]):
     initial = np.zeros((h, w), np.uint8)
     initial[:] = cv2.GC_BGD
     initial[mag0 == 255] = cv2.GC_FGD
-    for i, rect in enumerate(rects):
+    for rect in rects:
         cv2.drawContours(initial, [rect[4]], -1, int(cv2.GC_FGD), -1)
 
     initial[display[:, :, 0] > 0] = cv2.GC_PR_FGD
+    if 0 not in initial:
+        # Crude solution to https://github.com/NaturalHistoryMuseum/inselect/issues/370
+        # See also http://stackoverflow.com/a/7546787/1773758
+        # Only ever seen in one image
+        initial[0, :] = 0
     bgmodel = np.zeros((1, 65), np.float64)
     fgmodel = np.zeros((1, 65), np.float64)
     mask = initial
-    rect = None
-    cv2.grabCut(image, mask, rect, bgmodel, fgmodel, 1, cv2.GC_INIT_WITH_MASK)
+    cv2.grabCut(image, mask, None, bgmodel, fgmodel, 1, cv2.GC_INIT_WITH_MASK)
     mask2 = np.where((mask == 2) | (mask == 0), 0, 1).astype('uint8')
 
     contours, hierarchy = _find_contours(mask2.copy(),
diff --git a/inselect/tests/gui/test_subsegment.py b/inselect/tests/gui/test_subsegment.py
index d1610ed..605643a 100644
--- a/inselect/tests/gui/test_subsegment.py
+++ b/inselect/tests/gui/test_subsegment.py
@@ -4,11 +4,14 @@
 from mock import patch
 from pathlib import Path
 
+import cv2
+
 from PyQt5.QtCore import QPointF, QRect
 from PyQt5.QtWidgets import QMessageBox
 
 from inselect.gui.roles import MetadataRole, RectRole
 from inselect.gui.sort_document_items import SortDocumentItems
+from inselect.lib.segment import segment_grabcut
 
 from .gui_test import GUITest
 
@@ -95,5 +98,10 @@ def test_subsegment_no_seeds(self, mock_warning):
         self.assertTrue(expected in mock_warning.call_args[0])
 
 
+    def test_subsegment_grabcut_fail(self):
+        "Subsegment image that has caused problems for cv2's grabcut function"
+        # https://github.com/NaturalHistoryMuseum/inselect/issues/370
+        segment_grabcut(cv2.imread(str(TESTDATA / 'grabcut_problem.jpg')))
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/inselect/tests/test_data/grabcut_problem.jpg b/inselect/tests/test_data/grabcut_problem.jpg
new file mode 100644
index 0000000..90f549d
Binary files /dev/null and b/inselect/tests/test_data/grabcut_problem.jpg differ