diff --git a/bqskit/compiler/compile.py b/bqskit/compiler/compile.py
index c0073828f..c65743b9f 100644
--- a/bqskit/compiler/compile.py
+++ b/bqskit/compiler/compile.py
@@ -645,7 +645,7 @@ def type_and_check_input(input: CompilationInputLike) -> CompilationInput:
 
 def build_workflow(
     input: Circuit | UnitaryMatrix | StateVector | StateSystem,
-    model: MachineModel | None,
+    model: MachineModel | None = None,
     optimization_level: int = 1,
     synthesis_epsilon: float = 1e-8,
     max_synthesis_size: int = 3,