diff --git a/Tests/test_imagemorph.py b/Tests/test_imagemorph.py
index b51b212e0..89a4022ae 100644
--- a/Tests/test_imagemorph.py
+++ b/Tests/test_imagemorph.py
@@ -1,8 +1,7 @@
 # Test the ImageMorphology functionality
 from helper import unittest, PillowTestCase, hopper
 
-from PIL import Image
-from PIL import ImageMorph
+from PIL import Image, ImageMorph, _imagingmorph
 
 
 class MorphTests(PillowTestCase):
@@ -284,6 +283,23 @@ class MorphTests(PillowTestCase):
         # Assert
         self.assertEqual(mop.lut, lut)
 
+    def test_wrong_mode(self):
+        lut = ImageMorph.LutBuilder(op_name='corner').build_lut()
+        imrgb = Image.new('RGB', (10, 10))
+        iml = Image.new('L', (10, 10))
+
+        with self.assertRaises(ValueError):
+            _imagingmorph.apply(bytes(lut), imrgb.im.id, iml.im.id)
+
+        with self.assertRaises(ValueError):
+            _imagingmorph.apply(bytes(lut), iml.im.id, imrgb.im.id)
+
+        with self.assertRaises(ValueError):
+            _imagingmorph.match(bytes(lut), imrgb.im.id)
+
+        # Should not raise
+        _imagingmorph.match(bytes(lut), iml.im.id)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/src/_imagingmorph.c b/src/_imagingmorph.c
index 73979f635..0b60e4c80 100644
--- a/src/_imagingmorph.c
+++ b/src/_imagingmorph.c
@@ -64,14 +64,14 @@ apply(PyObject *self, PyObject* args)
     width = imgin->xsize;
     height = imgin->ysize;
 
-    if (imgin->type != IMAGING_TYPE_UINT8 &&
+    if (imgin->type != IMAGING_TYPE_UINT8 ||
         imgin->bands != 1) {
-        PyErr_SetString(PyExc_RuntimeError, "Unsupported image type");
+        PyErr_SetString(PyExc_ValueError, "Unsupported image type");
         return NULL;
     }
-    if (imgout->type != IMAGING_TYPE_UINT8 &&
+    if (imgout->type != IMAGING_TYPE_UINT8 ||
         imgout->bands != 1) {
-        PyErr_SetString(PyExc_RuntimeError, "Unsupported image type");
+        PyErr_SetString(PyExc_ValueError, "Unsupported image type");
         return NULL;
     }
 
@@ -167,9 +167,9 @@ match(PyObject *self, PyObject* args)
     lut = PyBytes_AsString(py_lut);
     imgin = (Imaging) i0;
 
-    if (imgin->type != IMAGING_TYPE_UINT8 &&
+    if (imgin->type != IMAGING_TYPE_UINT8 ||
         imgin->bands != 1) {
-        PyErr_SetString(PyExc_RuntimeError, "Unsupported image type");
+        PyErr_SetString(PyExc_ValueError, "Unsupported image type");
         return NULL;
     }