diff --git a/toolchain/mfc/build.py b/toolchain/mfc/build.py
index 94068d56f2..1f7644566b 100644
--- a/toolchain/mfc/build.py
+++ b/toolchain/mfc/build.py
@@ -105,6 +105,11 @@ def build_target(mfc, name: str, history: typing.List[str] = None):
     if history is None:
         history = []
 
+    if mfc.args["no_build"]:
+        cons.print("--no-build specified, skipping...")
+        cons.unindent()
+        return
+
     if name in history:
         cons.print("Already built, skipping...")
         cons.unindent()
diff --git a/toolchain/mfc/run/engines.py b/toolchain/mfc/run/engines.py
index 1c1a127f5f..49786cf4f7 100644
--- a/toolchain/mfc/run/engines.py
+++ b/toolchain/mfc/run/engines.py
@@ -57,7 +57,8 @@ def __init__(self) -> None:
 
     def _init(self) -> None:
         self.mpibin = mpi_bins.get_binary(self.mfc.args)
-        self.bWorks = False # We don't know yet whether this engine works
+        # If using MPI, we don't know yet whether this engine works
+        self.bKnowWorks = not self.mfc.args["mpi"]
 
     def get_args(self) -> str:
         return f"""\
@@ -79,7 +80,7 @@ def get_exec_cmd(self, target_name: str) -> typing.List[str]:
 
 
     def run(self, names: typing.List[str]) -> None:
-        if not self.bWorks:
+        if not self.bKnowWorks:
             # Fix MFlowCode/MFC#21: Check whether attempting to run a job will hang
             # forever. This can happen when using the wrong queue system.
 
@@ -102,11 +103,11 @@ def run(self, names: typing.List[str]) -> None:
             p.join(work_timeout)
 
             try:
-                self.bWorks = q.get(block=False)
+                self.bKnowWorks = q.get(block=False)
             except queue.Empty as e:
-                self.bWorks = False
+                self.bKnowWorks = False
 
-            if p.is_alive() or not self.bWorks:
+            if p.is_alive() or not self.bKnowWorks:
                 raise common.MFCException(
                       "The [bold magenta]Interactive Engine[/bold magenta] appears to hang or exit with a non-zero status code. "
                     + "This may indicate that the wrong MPI binary is being used to launch parallel jobs. You can specify the correct one for your system "