diff --git a/lib/iris/analysis/_interpolation.py b/lib/iris/analysis/_interpolation.py
index f3e1870427..7e255bd87e 100644
--- a/lib/iris/analysis/_interpolation.py
+++ b/lib/iris/analysis/_interpolation.py
@@ -571,13 +571,13 @@ def _points(self, sample_points, data, data_dims=None):
             # Transpose data in preparation for interpolation.
             data = np.transpose(data, interp_order)
 
-        # Interpolate the data, merging the chunks in the interpolated
-        # dimensions.
-        dims_merge_chunks = [dmap[d] for d in di]
+        # Interpolate the data, ensuring the interpolated dimensions
+        # are not chunked.
+        dims_not_chunked = [dmap[d] for d in di]
         result = map_complete_blocks(
             data,
             self._interpolate,
-            dims=dims_merge_chunks,
+            dims=dims_not_chunked,
             out_sizes=interp_shape,
             src_points=self._src_points,
             interp_points=interp_points,