diff --git a/skimage/exposure/_unwrap_2d.pyx b/skimage/exposure/_unwrap_2d.pyx
index 88983287..6e889729 100644
--- a/skimage/exposure/_unwrap_2d.pyx
+++ b/skimage/exposure/_unwrap_2d.pyx
@@ -1,12 +1,12 @@
-cdef extern void unwrap2D(float* wrapped_image,
-                     float* unwrapped_image,
+cdef extern void unwrap2D(double* wrapped_image,
+                     double* unwrapped_image,
                      unsigned char* input_mask,
                      int image_width, int image_height,
                      int wrap_around_x, int wrap_around_y)
 
-def unwrap_2d(float[:, ::1] image,
+def unwrap_2d(double[:, ::1] image,
               unsigned char[:, ::1] mask,
-              float[:, ::1] unwrapped_image,
+              double[:, ::1] unwrapped_image,
               wrap_around):
     unwrap2D(&image[0, 0],
              &unwrapped_image[0, 0],
diff --git a/skimage/exposure/unwrap.py b/skimage/exposure/unwrap.py
index a2a8c42a..039ae911 100644
--- a/skimage/exposure/unwrap.py
+++ b/skimage/exposure/unwrap.py
@@ -92,6 +92,8 @@ def unwrap_phase(image, wrap_around=False):
     if image.ndim == 1:
         unwrap_1d(image_not_masked, image_unwrapped)
     elif image.ndim == 2:
+        image_not_masked = np.asarray(image, dtype=np.float64, order='C')
+        image_unwrapped = np.empty_like(image, dtype=np.float64, order='C')
         unwrap_2d(image_not_masked, mask, image_unwrapped,
                   wrap_around)
     elif image.ndim == 3: