diff --git a/src/specify_cli/workflows/steps/if_then/__init__.py b/src/specify_cli/workflows/steps/if_then/__init__.py
index b2ed880678..d457e1d953 100644
--- a/src/specify_cli/workflows/steps/if_then/__init__.py
+++ b/src/specify_cli/workflows/steps/if_then/__init__.py
@@ -22,11 +22,11 @@ def execute(self, config: dict[str, Any], context: StepContext) -> StepResult:
         result = evaluate_condition(condition, context)
 
         if result:
-            branch_name = "then"
             branch = config.get("then", [])
+            branch_name = "then"
         else:
-            branch_name = "else"
             branch = config.get("else", [])
+            branch_name = "else"
 
         # The engine does not auto-validate step config (see
         # ``WorkflowEngine.load_workflow``), and it feeds ``next_steps`` straight
diff --git a/tests/test_workflows.py b/tests/test_workflows.py
index b1d9841535..75db91458d 100644
--- a/tests/test_workflows.py
+++ b/tests/test_workflows.py
@@ -2130,6 +2130,62 @@ def test_execute_else_branch(self):
         assert result.output["condition_result"] is False
         assert result.next_steps[0]["id"] == "b"
 
+    @pytest.mark.parametrize("bad_branch", ["oops", {"a": 1}, 42])
+    def test_execute_rejects_non_list_branch(self, bad_branch):
+        """execute() fails cleanly on a non-list then/else branch. The engine
+        doesn't auto-validate step config, so a non-iterable next_steps would
+        otherwise crash the run — completing the while/do-while guard (#3519) for
+        the if step (mirrors the switch step's 'cases' guard)."""
+        from specify_cli.workflows.steps.if_then import IfThenStep
+        from specify_cli.workflows.base import StepContext, StepStatus
+
+        step = IfThenStep()
+        cond = "{{ inputs.scope == 'full' }}"
+        res_then = step.execute(
+            {"id": "i", "condition": cond, "then": bad_branch},
+            StepContext(inputs={"scope": "full"}),
+        )
+        assert res_then.status is StepStatus.FAILED
+        assert "'then' must be a list" in (res_then.error or "")
+        res_else = step.execute(
+            {"id": "i", "condition": cond, "then": [], "else": bad_branch},
+            StepContext(inputs={"scope": "backend"}),
+        )
+        assert res_else.status is StepStatus.FAILED
+        assert "'else' must be a list" in (res_else.error or "")
+
+    def test_execute_allows_null_else_branch(self):
+        """`else: null` is the supported 'no else branch' form (validate accepts
+        it); a false condition must run cleanly (COMPLETED, no next steps), not
+        be turned into FAILED by the non-list guard."""
+        from specify_cli.workflows.steps.if_then import IfThenStep
+        from specify_cli.workflows.base import StepContext, StepStatus
+
+        step = IfThenStep()
+        result = step.execute(
+            {"id": "i", "condition": "{{ inputs.scope == 'full' }}",
+             "then": [{"id": "a", "command": "speckit.tasks"}], "else": None},
+            StepContext(inputs={"scope": "backend"}),
+        )
+        assert result.status is StepStatus.COMPLETED
+        assert result.output["condition_result"] is False
+        assert result.next_steps == []
+
+    def test_execute_null_then_is_failed_not_normalized(self):
+        """Only `else: null` is normalized to []; `then: null` is invalid
+        (validate() rejects it), so a true condition must FAIL, not silently
+        complete an empty branch."""
+        from specify_cli.workflows.steps.if_then import IfThenStep
+        from specify_cli.workflows.base import StepContext, StepStatus
+
+        step = IfThenStep()
+        result = step.execute(
+            {"id": "i", "condition": "{{ inputs.scope == 'full' }}", "then": None},
+            StepContext(inputs={"scope": "full"}),
+        )
+        assert result.status is StepStatus.FAILED
+        assert "'then' must be" in (result.error or "")
+
     def test_validate_missing_condition(self):
         from specify_cli.workflows.steps.if_then import IfThenStep