diff --git a/unbundle b/unbundle
index aa175d7..b8eb8f1 100755
--- a/unbundle
+++ b/unbundle
@@ -19,9 +19,15 @@ def resolve_includes(bundle_name, bundle_path, bundles=False):
         packages_f = os.path.join(bundle_path, "packages")
         if not os.path.exists(packages_f):
             # pundle definition file does not exist
-            return set()
+            print(f"ERROR: could not find {bundle_name} bundle")
+            return set(), False
+
         # find name on its own line
-        return set([bundle_name]) if f"\n{bundle_name}\n" in open(packages_f, "r").read() else set()
+        if f"\n{bundle_name}\n" in open(packages_f, "r").read():
+            return set([bundle_name]), True
+
+        print(f"ERROR: could not find {bundle_name} bundle")
+        return set(), False
 
     packages = set()
     for line in lines:
@@ -31,7 +37,14 @@ def resolve_includes(bundle_name, bundle_path, bundles=False):
 
         if line.startswith("include("):
             inc_bundle = line[len("include("):].rsplit(")")[0]
-            packages = packages.union(resolve_includes(inc_bundle, bundle_path, bundles))
+            try:
+                n_packages, success = resolve_includes(inc_bundle, bundle_path, bundles)
+                if not success:
+                    return set(), False
+                packages = packages.union(n_packages)
+            except RecursionError:
+                print("ERROR: include loop found")
+                return set(), False
             if bundles:
                 packages.add(inc_bundle)
 
@@ -40,7 +53,7 @@ def resolve_includes(bundle_name, bundle_path, bundles=False):
         if not bundles:
             packages.add(line)
 
-    return packages
+    return packages, True
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(description='Process bundle packages following includes')
@@ -49,10 +62,17 @@ if __name__ == "__main__":
     parser.add_argument('--bundles', default=False, action='store_true',
                         help='Report only included bundle names')
     args = parser.parse_args()
+    success = True
     if args.bundles:
         os_core_set = set(["os-core"])
     else:
-        os_core_set = resolve_includes("os-core", args.bundle_path)
+        os_core_set, success = resolve_includes("os-core", args.bundle_path)
+
+    if not success:
+        sys.exit(1)
+
+    bundle_set, success = resolve_includes(args.bundle_name, args.bundle_path, bundles=args.bundles)
+    if not success:
+        sys.exit(1)
 
-    bundle_set = resolve_includes(args.bundle_name, args.bundle_path, bundles=args.bundles)
     print('\n'.join(sorted(os_core_set.union(bundle_set))))