diff --git a/skimage/restoration/_unwrap_2d.pyx b/skimage/restoration/_unwrap_2d.pyx
index 6e889729..6e486439 100644
--- a/skimage/restoration/_unwrap_2d.pyx
+++ b/skimage/restoration/_unwrap_2d.pyx
@@ -1,8 +1,9 @@
-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)
+cdef extern from *:
+    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(double[:, ::1] image,
               unsigned char[:, ::1] mask,
diff --git a/skimage/restoration/_unwrap_3d.pyx b/skimage/restoration/_unwrap_3d.pyx
index 370d58be..3a1869a8 100644
--- a/skimage/restoration/_unwrap_3d.pyx
+++ b/skimage/restoration/_unwrap_3d.pyx
@@ -1,8 +1,9 @@
-cdef extern void unwrap3D(double* wrapped_volume,
-                     double* unwrapped_volume,
-                     unsigned char* input_mask,
-                     int image_width, int image_height, int volume_depth,
-                     int wrap_around_x, int wrap_around_y, int wrap_around_z)
+cdef extern from *:
+  void unwrap3D(double* wrapped_volume,
+                double* unwrapped_volume,
+                unsigned char* input_mask,
+                int image_width, int image_height, int volume_depth,
+                int wrap_around_x, int wrap_around_y, int wrap_around_z)
 
 def unwrap_3d(double[:, :, ::1] image,
               unsigned char[:, :, ::1] mask,