diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29b..ae01f95b 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    fixed:
+    - Bug causing YAML tests to not populate `Simulation.input_variables`.
diff --git a/policyengine_core/simulations/simulation_builder.py b/policyengine_core/simulations/simulation_builder.py
index 5f6835d0..b39e953f 100644
--- a/policyengine_core/simulations/simulation_builder.py
+++ b/policyengine_core/simulations/simulation_builder.py
@@ -79,14 +79,23 @@ def build_from_dict(
             key in tax_benefit_system.entities_plural()
             for key in input_dict.keys()
         ):
-            return self.build_from_entities(
+            simulation = self.build_from_entities(
                 tax_benefit_system, input_dict, simulation
             )
         else:
-            return self.build_from_variables(
+            simulation = self.build_from_variables(
                 tax_benefit_system, input_dict, simulation
             )
 
+        simulation.input_variables = [
+            variable.name
+            for variable in simulation.tax_benefit_system.variables.values()
+            if len(simulation.get_holder(variable.name).get_known_periods())
+            > 0
+        ]
+
+        return simulation
+
     def build_from_entities(
         self,
         tax_benefit_system: "TaxBenefitSystem",