diff --git a/skimage/_shared/safe_as_int.py b/skimage/_shared/_safe_as_int.py
similarity index 98%
rename from skimage/_shared/safe_as_int.py
rename to skimage/_shared/_safe_as_int.py
index 0d665f9f..200d6efb 100644
--- a/skimage/_shared/safe_as_int.py
+++ b/skimage/_shared/_safe_as_int.py
@@ -3,7 +3,7 @@ import numpy as np
 __all__ = ['_safe_as_int']
 
 
-def _safe_as_int(val, atol=1e-7):
+def safe_as_int(val, atol=1e-3):
     """
     Attempt to safely cast values to integer format.
 
diff --git a/skimage/_shared/utils.py b/skimage/_shared/utils.py
index 9148e7ff..f94edfc5 100644
--- a/skimage/_shared/utils.py
+++ b/skimage/_shared/utils.py
@@ -5,8 +5,10 @@ import sys
 import six
 
 from ._warnings import all_warnings
+from ._safe_as_int import safe_as_int
 
-__all__ = ['deprecated', 'get_bound_method_class', 'all_warnings']
+__all__ = ['deprecated', 'get_bound_method_class', 'all_warnings',
+           'safe_as_int']
 
 
 class skimage_deprecation(Warning):
diff --git a/skimage/transform/_geometric.py b/skimage/transform/_geometric.py
index 53074c00..6eb0f70a 100644
--- a/skimage/transform/_geometric.py
+++ b/skimage/transform/_geometric.py
@@ -4,7 +4,7 @@ import warnings
 import numpy as np
 from scipy import ndimage, spatial
 
-from skimage._shared.utils import get_bound_method_class
+from skimage._shared.utils import get_bound_method_class, safe_as_int
 from skimage.util import img_as_float
 from ._warps_cy import _warp_fast
 
@@ -1078,7 +1078,7 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
     if output_shape is None:
         output_shape = ishape
     else:
-        output_shape = np.array(output_shape, dtype=int)
+        output_shape = safe_as_int(output_shape)
 
 
     out = None
diff --git a/skimage/transform/tests/test_warps.py b/skimage/transform/tests/test_warps.py
index f85125d0..07054ab7 100644
--- a/skimage/transform/tests/test_warps.py
+++ b/skimage/transform/tests/test_warps.py
@@ -250,7 +250,11 @@ def test_inverse():
 
 def test_slow_warp_nonint_oshape():
     image = np.random.random((5, 5))
-    warp(image, lambda xy: xy, output_shape=(13.1, 19.5))
+
+    assert_raises(ValueError, warp, image, lambda xy: xy,
+                  output_shape=(13.1, 19.5))
+
+    warp(image, lambda xy: xy, output_shape=(13.0001, 19.9999))
 
 
 if __name__ == "__main__":