diff --git a/toolchain/mfc/case.py b/toolchain/mfc/case.py
index 44a1da570e..e770e5b24b 100644
--- a/toolchain/mfc/case.py
+++ b/toolchain/mfc/case.py
@@ -391,7 +391,7 @@ def __get_sim_fpp(self, print: bool) -> str:
 #:set num_dims              = {num_dims}
 #:set num_vels              = {num_vels}
 #:set nterms                = {nterms}
-#:set num_fluids            = {int(self.params["num_fluids"])}
+#:set num_fluids            = {int(self.params.get("num_fluids", 1))}
 #:set wenojs                = {wenojs}
 #:set mapped_weno           = {mapped_weno}
 #:set wenoz                 = {wenoz}