diff --git a/lib/cartopy/mpl/geoaxes.py b/lib/cartopy/mpl/geoaxes.py
index 249d50fbf..c2fc01327 100644
--- a/lib/cartopy/mpl/geoaxes.py
+++ b/lib/cartopy/mpl/geoaxes.py
@@ -1332,24 +1332,25 @@ def imshow(self, img, *args, **kwargs):
             kwargs['alpha'] = alpha
 
             # As a workaround to a matplotlib limitation, turn any images
-            # which are RGB(A) with a mask into unmasked RGBA images with alpha
-            # put into the A channel.
+            # which are masked array RGB(A) into RGBA images
+
             if np.ma.is_masked(img) and len(img.shape) > 2:
-                # if we don't pop alpha, imshow will apply (erroneously?) a
-                # 1D alpha to the RGBA array
-                # kwargs['alpha'] is guaranteed to be either 1D, 2D, or None
-                alpha = kwargs.pop('alpha')
-                old_img = img[:, :, 0:3]
-                img = np.zeros(img.shape[:2] + (4, ), dtype=img.dtype)
-                img[:, :, 0:3] = old_img
-                # Put an alpha channel in if the image was masked.
-                if not np.any(alpha):
-                    alpha = 1
-                img[:, :, 3] = np.ma.filled(alpha, fill_value=0) * \
-                    (~np.any(old_img.mask, axis=2))
-                if img.dtype.kind == 'u':
+
+                # transform RGB(A) into RGBA
+                old_img = img
+                img = np.ones(old_img.shape[:2] + (4, ),
+                              dtype=old_img.dtype)
+                img[:, :, :3] = old_img[:, :, :3]
+
+                # if img is RGBA, save alpha channel
+                if old_img.shape[-1] == 4:
+                    img[:, :, 3] = old_img[:, :, 3]
+                elif img.dtype.kind == 'u':
                     img[:, :, 3] *= 255
 
+                # apply the mask to the A channel
+                img[np.any(old_img[:, :, :3].mask, axis=2), 3] = 0
+
             result = super().imshow(img, *args, extent=extent, **kwargs)
 
         return result
diff --git a/lib/cartopy/tests/mpl/test_images.py b/lib/cartopy/tests/mpl/test_images.py
index 830af6e66..c46c4ef27 100644
--- a/lib/cartopy/tests/mpl/test_images.py
+++ b/lib/cartopy/tests/mpl/test_images.py
@@ -154,6 +154,22 @@ def test_imshow_rgba():
     assert sum(img.get_array().data[:, 0, 3]) == 0
 
 
+def test_imshow_rgba_alpha():
+    # test that alpha channel from RGBA is not skipped
+    dy, dx = (3, 4)
+
+    ax = plt.axes(projection=ccrs.Orthographic(-120, 45))
+
+    # Create RGBA Image with random data and linspace alpha
+    RGBA = np.linspace(0, 255*31, dx*dy*4, dtype=np.uint8).reshape((dy, dx, 4))
+
+    alpha = np.array([0, 85, 170, 255])
+    RGBA[:, :, 3] = alpha
+
+    img = ax.imshow(RGBA, transform=ccrs.PlateCarree())
+    assert np.all(np.unique(img.get_array().data[:, :, 3]) == alpha)
+
+
 def test_imshow_rgb():
     # tests that the alpha of a RGB array passed to imshow is set to 0
     # instead of masked