diff --git a/tools/doc_census_check.py b/tools/doc_census_check.py
index 1574ae3..bc26980 100644
--- a/tools/doc_census_check.py
+++ b/tools/doc_census_check.py
@@ -1828,10 +1828,15 @@ def main():
             units[name].update(k for k in entry[0][0] if k in keep)
         observed = sum(len(v) for v in seen.values())
         kept = sum(len(v) for v in units.values())
-        with open(a.save_vocab, "w", encoding="utf-8") as fh:
-            json.dump({"rev": a.rev, "repo": a.repo,
-                       "tools": {k: sorted(v) for k, v in units.items()}},
-                      fh, indent=1, sort_keys=True)
+        try:
+            with open(a.save_vocab, "w", encoding="utf-8") as fh:
+                json.dump({"rev": a.rev, "repo": a.repo,
+                           "tools": {k: sorted(v) for k, v in units.items()}},
+                          fh, indent=1, sort_keys=True)
+        except OSError as exc:
+            print("cannot write --save-vocab " + a.save_vocab + ": " + str(exc),
+                  file=sys.stderr)
+            return 2
         print(f"wrote vocabulary {a.save_vocab}: {len(units)} tool(s), "
               f"{kept} unit(s) at {a.rev} ({observed} key(s) observed, "
               f"{observed - kept} unspendable by any claim)")
diff --git a/tools/queue_index.py b/tools/queue_index.py
index 698b23f..844818b 100644
--- a/tools/queue_index.py
+++ b/tools/queue_index.py
@@ -578,8 +578,12 @@ def run(args):
         return 0
 
     if args.write:
-        with open(args.write, "w", encoding="utf-8") as fh:
-            fh.write(build_doc(payload))
+        try:
+            with open(args.write, "w", encoding="utf-8") as fh:
+                fh.write(build_doc(payload))
+        except OSError as exc:
+            print("cannot write --write " + args.write + ": " + str(exc), file=sys.stderr)
+            return 2
         print("wrote %s (%d bytes)" % (args.write, os.path.getsize(args.write)))
         return 0
 
diff --git a/tools/tool_map.py b/tools/tool_map.py
index 2699e5f..a58926d 100644
--- a/tools/tool_map.py
+++ b/tools/tool_map.py
@@ -507,8 +507,12 @@ def main():
         print(f"tool_map: wrote {args.json}")
 
     if args.write:
-        with open(args.write, "w", encoding="utf-8") as fh:
-            fh.write(text)
+        try:
+            with open(args.write, "w", encoding="utf-8") as fh:
+                fh.write(text)
+        except OSError as exc:
+            print("cannot write --write " + args.write + ": " + str(exc), file=sys.stderr)
+            return 2
         print(f"tool_map: wrote {args.write} ({len(text)} B, "
               f"{len(data['rows'])} tools, {len(data['legs'])} gate legs)")
         return 0