diff --git a/pysteps/blending/steps.py b/pysteps/blending/steps.py
index 2d153510..2e57b26b 100644
--- a/pysteps/blending/steps.py
+++ b/pysteps/blending/steps.py
@@ -711,9 +711,9 @@ def worker(j):
                             )
                         )
 
-                    final_blended_forecast_all_members_one_timestep[j] = (
-                        final_blended_forecast_single_member
-                    )
+                final_blended_forecast_all_members_one_timestep[j] = (
+                    final_blended_forecast_single_member
+                )
 
             dask_worker_collection = []
 
diff --git a/pysteps/tests/test_blending_steps.py b/pysteps/tests/test_blending_steps.py
index abfa5522..ea67bf12 100644
--- a/pysteps/tests/test_blending_steps.py
+++ b/pysteps/tests/test_blending_steps.py
@@ -17,6 +17,10 @@
     (1, 3, 4, 8,'steps', None, "mean", False, "spn", True, 4, False, False, 0, True, None, None, None),
     (1, 3, 4, 8,'steps', None, "cdf", False, "spn", True, 4, False, False, 0, False, None, None, None),
     (1, [1, 2, 3], 4, 8,'steps', None, "cdf", False, "spn", True, 4, False, False, 0, False, None, None, None),
+    # Regression test for a gap in the timesteps list (e.g. [1, 3] skips 2): this used to raise
+    # "TypeError: 'NoneType' object is not iterable" because the bin for the skipped step never
+    # got a value written to final_blended_forecast_all_members_one_timestep.
+    (1, [1, 3], 4, 8,'steps', None, "cdf", False, "spn", True, 4, False, False, 0, False, None, None, None),
     (1, 3, 4, 8,'steps', "incremental", "cdf", False, "spn", True, 4, False, False, 0, False, None, None, None),
     (1, 3, 4, 6,'steps', "incremental", "cdf", False, "bps", True, 4, False, False, 0, False, None, None, None),
     (1, 3, 4, 6,'steps', "incremental", "cdf", False, "bps", False, 4, False, False, 0, False, None, None, None),