diff --git a/skimage/util/tests/test_dtype.py b/skimage/util/tests/test_dtype.py
index d5067981..e42030b0 100644
--- a/skimage/util/tests/test_dtype.py
+++ b/skimage/util/tests/test_dtype.py
@@ -9,8 +9,8 @@ dtype_range = {np.uint8: (0, 255),
                np.uint16: (0, 65535),
                np.int8: (-128, 127),
                np.int16: (-32768, 32767),
-               np.float32: (0, 1),
-               np.float64: (0, 1)}
+               np.float32: (-1.0, 1.0),
+               np.float64: (-1.0, 1.0)}
 
 def _verify_range(msg, x, vmin, vmax):
     assert_equal(x[0], vmin)
@@ -29,8 +29,9 @@ def test_range():
 
             omin, omax = dtype_range[dt]
 
-            if imin == 0:
+            if imin == 0 or omin == 0:
                 omin = 0
+                imin = 0
 
             yield _verify_range, \
                   "From %s to %s" % (np.dtype(dtype), np.dtype(dt)), \
@@ -67,13 +68,6 @@ def test_unsupported_dtype():
     assert_raises(ValueError, img_as_int, x)
 
 
-def test_float_out_of_range():
-    too_high = np.array([2], dtype=np.float32)
-    assert_raises(ValueError, img_as_int, too_high)
-    too_low = np.array([-1], dtype=np.float32)
-    assert_raises(ValueError, img_as_int, too_low)
-
-
 def test_copy():
     x = np.array([1], dtype=np.float64)
     y = img_as_float(x)
@@ -84,4 +78,3 @@ def test_copy():
 
 if __name__ == '__main__':
     np.testing.run_module_suite()
-