diff --git a/src/anemoi/inference/metadata.py b/src/anemoi/inference/metadata.py
index f521825..967adab 100644
--- a/src/anemoi/inference/metadata.py
+++ b/src/anemoi/inference/metadata.py
@@ -629,12 +629,11 @@ def constant_forcings_inputs(self, context, input_state):
         remaining_mask = [i for i, _ in remaining]
         remaining = [name for _, name in remaining]
 
-        result.append(
-            context.create_constant_coupled_forcings(
-                remaining,
-                remaining_mask,
-            )
-        )
+        forcing = context.create_constant_coupled_forcings(remaining, remaining_mask)
+
+        if forcing is not None:
+            # SimpleRunner does not support dynamic forcings
+            result.append(forcing)
 
         return result
 
@@ -676,12 +675,12 @@ def dynamic_forcings_inputs(self, context, input_state):
         remaining_mask = [i for i, _ in remaining]
         remaining = [name for _, name in remaining]
 
-        result.append(
-            context.create_dynamic_coupled_forcings(
-                remaining,
-                remaining_mask,
-            )
-        )
+        forcing = context.create_dynamic_coupled_forcings(remaining, remaining_mask)
+
+        if forcing is not None:
+            # SimpleRunner does not support dynamic forcings
+            result.append(forcing)
+
         return result
 
     def boundary_forcings_inputs(self, context, input_state):
diff --git a/src/anemoi/inference/runner.py b/src/anemoi/inference/runner.py
index b1c6b95..b5cba45 100644
--- a/src/anemoi/inference/runner.py
+++ b/src/anemoi/inference/runner.py
@@ -145,9 +145,6 @@ def add_initial_forcings_to_input_state(self, input_state):
         # TODO: Check for user provided forcings
 
         for source in self.constant_forcings_inputs:
-            if source is None:
-                # When the constants are already in the input state
-                continue
             LOG.info("Constant forcings input: %s %s (%s)", source, source.variables, dates)
             arrays = source.load_forcings(input_state, dates)
             for name, forcing in zip(source.variables, arrays):
@@ -362,6 +359,7 @@ def add_dynamic_forcings_to_input_tensor(self, input_tensor_torch, state, date,
         # batch is always 1
 
         for source in self.dynamic_forcings_inputs:
+
             forcings = source.load_forcings(state, [date])  # shape: (variables, dates, values)
 
             forcings = np.squeeze(forcings, axis=1)  # Drop the dates dimension
diff --git a/src/anemoi/inference/runners/simple.py b/src/anemoi/inference/runners/simple.py
index f0dd5c9..1907d8d 100644
--- a/src/anemoi/inference/runners/simple.py
+++ b/src/anemoi/inference/runners/simple.py
@@ -52,4 +52,15 @@ def create_dynamic_computed_forcings(self, variables, mask):
         return result
 
     def create_constant_coupled_forcings(self, variables, mask):
+        # This runner does not support coupled forcings
+        # there are supposed to be already in the state dictionary
+        # of managed by the user.
+        LOG.warning("Coupled forcings are not supported by this runner: %s", variables)
+        return None
+
+    def create_dynamic_coupled_forcings(self, variables, mask):
+        # This runner does not support coupled forcings
+        # there are supposed to be already in the state dictionary
+        # of managed by the user.
+        LOG.warning("Coupled forcings are not supported by this runner: %s", variables)
         return None