diff --git a/src/v/kafka/protocol/CMakeLists.txt b/src/v/kafka/protocol/CMakeLists.txt
index 0fc9abe4b514..4d9ff8fc61b9 100644
--- a/src/v/kafka/protocol/CMakeLists.txt
+++ b/src/v/kafka/protocol/CMakeLists.txt
@@ -7,14 +7,14 @@ foreach(schema ${schemata})
   get_filename_component(msg_name ${schema} NAME_WE)
   set(schema_src ${CMAKE_CURRENT_SOURCE_DIR}/schemata/${schema})
   set(msg_dir "${CMAKE_CURRENT_BINARY_DIR}/schemata")
-  set(msg_srcs
-    "${msg_dir}/${msg_name}.h"
-    "${msg_dir}/${msg_name}.cc")
-  list(APPEND message_srcs ${msg_srcs})
+  set(msg_hdr "${msg_dir}/${msg_name}.h")
+  set(msg_src "${msg_dir}/${msg_name}.cc")
+  list(APPEND message_srcs ${msg_hdr})
+  list(APPEND message_srcs ${msg_src})
   add_custom_command(
-    OUTPUT ${msg_srcs}
+    OUTPUT ${msg_hdr} ${msg_src}
     COMMAND ${KAFKA_CODEGEN_VENV} ${message_gen}
-    ARGS ${msg_dir} ${schema_src}
+    ARGS ${schema_src} ${msg_hdr} ${msg_src}
     DEPENDS ${schema_src} ${message_gen} ${KAFKA_CODEGEN_VENV}
     COMMENT "Running kafka request codegen on ${schema_src}"
     VERBATIM)
diff --git a/src/v/kafka/protocol/schemata/generator.py b/src/v/kafka/protocol/schemata/generator.py
old mode 100644
new mode 100755
index 12481a57b75a..ce78c6379423
--- a/src/v/kafka/protocol/schemata/generator.py
+++ b/src/v/kafka/protocol/schemata/generator.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+#
 # Copyright 2020 Redpanda Data, Inc.
 #
 # Use of this software is governed by the Business Source License
@@ -1501,11 +1503,10 @@ def parse_flexible_versions(flex_version):
 
 
 if __name__ == "__main__":
-    assert len(sys.argv) == 3
-    outdir = pathlib.Path(sys.argv[1])
-    schema_path = pathlib.Path(sys.argv[2])
-    src = (outdir / schema_path.name).with_suffix(".cc")
-    hdr = (outdir / schema_path.name).with_suffix(".h")
+    assert len(sys.argv) == 4
+    schema_path = pathlib.Path(sys.argv[1])
+    hdr = pathlib.Path(sys.argv[2])
+    src = pathlib.Path(sys.argv[3])
 
     # remove comments from the json file. comments are a non-standard json
     # extension that is not supported by the python json parser.