diff --git a/assemblers/org.osbuild.qemu b/assemblers/org.osbuild.qemu
index 1d383892..f568f07d 100755
--- a/assemblers/org.osbuild.qemu
+++ b/assemblers/org.osbuild.qemu
@@ -305,6 +305,8 @@ class PartitionTable:
             prep_type = "41"
         elif self.label == "gpt":
             prep_type = "9E1A2D38-C612-4316-AA26-8B49521E5A8B"
+        else:
+            raise RuntimeError(f"Unknown partition table type: {self.label}")
 
         for part in self.partitions:
             if part.type.upper() == prep_type:
diff --git a/inputs/org.osbuild.tree b/inputs/org.osbuild.tree
index f954f309..8d456838 100755
--- a/inputs/org.osbuild.tree
+++ b/inputs/org.osbuild.tree
@@ -79,6 +79,7 @@ class TreeInput(inputs.InputService):
         # and we have exactly one reference, i.e. a pipeline id
         pid, _ = refs.popitem()
 
+        path = None
         if pid:
             path = store.read_tree_at(pid, target)
 
diff --git a/stages/org.osbuild.sfdisk b/stages/org.osbuild.sfdisk
index 188cdc88..a669ea7e 100755
--- a/stages/org.osbuild.sfdisk
+++ b/stages/org.osbuild.sfdisk
@@ -53,6 +53,8 @@ class PartitionTable:
             prep_type = "41"
         elif self.label == "gpt":
             prep_type = "9E1A2D38-C612-4316-AA26-8B49521E5A8B"
+        else:
+            raise RuntimeError(f"Unknown partition table type: {self.label}")
 
         for part in self.partitions:
             if part.type.upper() == prep_type:
diff --git a/stages/org.osbuild.systemd.unit b/stages/org.osbuild.systemd.unit
index c4512a7a..dd9f295b 100755
--- a/stages/org.osbuild.systemd.unit
+++ b/stages/org.osbuild.systemd.unit
@@ -20,6 +20,10 @@ def main(tree, options):
         unit_dropins_dir = f"{tree}/usr/lib/systemd/system/{unit}.d"
     elif unit_type == "global":
         unit_dropins_dir = f"{tree}/usr/lib/systemd/user/{unit}.d"
+    else:
+        print(f"Error: Unknown unit type: {unit_type}")
+        return 1
+
     os.makedirs(unit_dropins_dir, exist_ok=True)
 
     # We trick configparser into letting us write multiple instances of the same option by writing them as keys with no
diff --git a/test/mod/test_meta.py b/test/mod/test_meta.py
index 419199a6..9901e6db 100644
--- a/test/mod/test_meta.py
+++ b/test/mod/test_meta.py
@@ -206,6 +206,7 @@ def make_fake_meta_json(tmp_path, name, version, invalid=""):
         "not": "following schema"
         """
 
+    # pylint: disable=possibly-used-before-assignment
     meta_json_path.write_text("""
     {
       "summary": "some json summary",