diff --git a/edalize/flows/generic.py b/edalize/flows/generic.py
index 9166d9a2d..76feb4a85 100644
--- a/edalize/flows/generic.py
+++ b/edalize/flows/generic.py
@@ -37,7 +37,7 @@ def get_tool_options(cls, flow_options):
 
     def configure_flow(self, flow_options):
         # Check for mandatory flow option "tool"
-        tool = self.flow_options.get("tool", "")
+        tool = self._require_flow_option(flow_options, "tool")
 
         # Apply flow-defined tool options if any
         fdto = self.FLOW_DEFINED_TOOL_OPTIONS.get(tool, {})
diff --git a/tests/flows/sim/Makefile b/tests/flows/sim/Makefile
new file mode 100644
index 000000000..2cfd5f672
--- /dev/null
+++ b/tests/flows/sim/Makefile
@@ -0,0 +1,19 @@
+#Auto generated by Edalize
+
+all: post_build
+
+pre_build: 
+
+design: sv_file.sv vlog_file.v vlog05_file.v vlog_incfile another_sv_file.sv design.scr | pre_build
+	$(EDALIZE_LAUNCHER) iverilog -stop_module -c design.scr -o design
+
+run: design
+	$(EDALIZE_LAUNCHER) vvp -n -M. design -fst $(EXTRA_OPTIONS)
+
+post_build: design
+
+pre_run: 
+
+run: pre_run
+
+post_run: run
diff --git a/tests/flows/sim/design.scr b/tests/flows/sim/design.scr
new file mode 100644
index 000000000..ecd8d98ba
--- /dev/null
+++ b/tests/flows/sim/design.scr
@@ -0,0 +1,11 @@
++define+vlogdefine_bool=1
++define+vlogdefine_int=42
++define+vlogdefine_str=hello
++parameter+top_module.vlogparam_bool=1
++parameter+top_module.vlogparam_int=42
++parameter+top_module.vlogparam_str="hello"
++incdir+.
+sv_file.sv
+vlog_file.v
+vlog05_file.v
+another_sv_file.sv
diff --git a/tests/test_flow_sim.py b/tests/test_flow_sim.py
new file mode 100644
index 000000000..d1dd6d089
--- /dev/null
+++ b/tests/test_flow_sim.py
@@ -0,0 +1,22 @@
+import pytest
+from .edalize_flow_common import flow_fixture
+
+
+def test_sim_no_tool(flow_fixture):
+    flow_options = {}
+    with pytest.raises(RuntimeError) as e:
+        ff = flow_fixture("sim", flow_options=flow_options)
+    assert "Flow 'sim' requires flow option 'tool' to be set" in str(e.value)
+
+
+def test_sim(flow_fixture):
+    flow_options = {"tool": "icarus"}
+    ff = flow_fixture("sim", flow_options=flow_options)
+
+    ff.flow.configure()
+    ff.compare_config_files(
+        [
+            "design.scr",
+            "Makefile",
+        ]
+    )