diff --git a/src/dvsim/job/deploy.py b/src/dvsim/job/deploy.py
index 71247b85..11779688 100644
--- a/src/dvsim/job/deploy.py
+++ b/src/dvsim/job/deploy.py
@@ -73,10 +73,14 @@ def __init__(self, sim_cfg: "SimCfg") -> None:
         self.sim_cfg = sim_cfg
         self.flow = sim_cfg.name
 
-        if not hasattr(self.sim_cfg, "variant"):
-            self.sim_cfg.variant = ""
+        # The sim_cfg argument might be a SimCfg, in which case it might define
+        # a variant. We don't depend on this, though: if sim_cfg is an instance
+        # of some other subclass of FlowCfg, just take an empty "variant".
+        self._variant: str | None = getattr(self.sim_cfg, "variant", None)
+        if not (isinstance(self._variant, str) or self._variant is None):
+            raise TypeError("Unexpected type for variant")
 
-        self._variant_suffix = f"_{self.sim_cfg.variant}" if self.sim_cfg.variant else ""
+        self._variant_suffix = f"_{self._variant}" if self._variant is not None else ""
 
         # A list of jobs on which this job depends.
         self.dependencies = []
@@ -106,6 +110,22 @@ def __init__(self, sim_cfg: "SimCfg") -> None:
 
     def get_job_spec(self) -> "JobSpec":
         """Get the job spec for this deployment."""
+        # If the FlowCfg object in self.sim_cfg doesn't have a links dictionary, default to {}.
+        links = getattr(self.sim_cfg, "links", {})
+
+        # Get commit and commit_short arguments to pass to JobSpec. We don't
+        # necessarily know that self.sim_cfg is actually a SimCfg object, so it
+        # might not have them defined. If it doesn't, we can't generate a
+        # meaningful job spec.
+        commit: str = self.sim_cfg.commit
+        commit_short: str = self.sim_cfg.commit_short
+        if not (commit and commit_short):
+            msg = (
+                "Cannot generate job spec. FlowCfg object "
+                "commit/commit_short is {commit}/{commit_short}."
+            )
+            raise TypeError(msg)
+
         return JobSpec(
             name=self.name,
             job_type=self.__class__.__name__,
@@ -115,9 +135,9 @@ def get_job_spec(self) -> "JobSpec":
             qual_name=self.qual_name,
             block=IPMeta(
                 name=self.sim_cfg.name,
-                variant=self.sim_cfg.variant,
-                commit=self.sim_cfg.commit,
-                commit_short=self.sim_cfg.commit_short,
+                variant=self._variant,
+                commit=commit,
+                commit_short=commit_short,
                 branch=self.sim_cfg.branch,
                 url="",
                 revision_info=self.sim_cfg.revision,
@@ -143,7 +163,7 @@ def get_job_spec(self) -> "JobSpec":
             odir=self.odir,
             renew_odir=self.renew_odir,
             log_path=Path(f"{self.odir}/{self.target}.log"),
-            links=self.sim_cfg.links,
+            links=links,
             pre_launch=self.pre_launch(),
             post_finish=self.post_finish(),
             pass_patterns=self.pass_patterns,