diff --git a/scripts/make_generated_files.py b/scripts/make_generated_files.py
index 73570fb28..d919fb0cf 100755
--- a/scripts/make_generated_files.py
+++ b/scripts/make_generated_files.py
@@ -27,7 +27,7 @@ class GenerationScript:
     def __init__(self, script: Path, files: List[Path],
                  output_dir_option: Optional[str] = None,
                  output_file_option: Optional[str] = None,
-                 optional: bool = False):
+                 optional: bool = False) -> None:
         # Path from the root of Mbed TLS or TF-PSA-Crypto of the generation script
         self.script = script
 
@@ -55,7 +55,7 @@ def __init__(self, script: Path, files: List[Path],
         # consuming repository hasn't been updated yet.
         self.optional = optional
 
-def get_generation_script_files(generation_script: str):
+def get_generation_script_files(generation_script: str) -> List[Path]:
     """
     Get the list of the default paths of the files that a given script
     generates. It is assumed that the script supports the "--list" option.
@@ -182,7 +182,7 @@ def get_generation_script_files(generation_script: str):
                 get_generation_script_files("scripts/generate_visualc_files.pl"),
                 "--directory", None))
 
-def get_generated_files(generation_scripts: List[GenerationScript]):
+def get_generated_files(generation_scripts: List[GenerationScript]) -> List[Path]:
     """
     List the generated files in Mbed TLS or TF-PSA-Crypto. The path from root
     is returned for each generated files.
@@ -193,7 +193,7 @@ def get_generated_files(generation_scripts: List[GenerationScript]):
 
     return files
 
-def make_generated_files(generation_scripts: List[GenerationScript]):
+def make_generated_files(generation_scripts: List[GenerationScript]) -> None:
     """
     Generate the configuration independent files in their default location in
     the Mbed TLS or TF-PSA-Crypto tree.
@@ -201,11 +201,13 @@ def make_generated_files(generation_scripts: List[GenerationScript]):
     for generation_script in generation_scripts:
         subprocess.run([generation_script.exe, str(generation_script.script)], check=True)
 
-def check_generated_files(generation_scripts: List[GenerationScript], root: Path):
+def check_generated_files(generation_scripts: List[GenerationScript],
+                          root: Path) -> bool:
     """
     Check that the given root directory contains the generated files as expected/
     generated by this script.
     """
+    ok = True
     for generation_script in generation_scripts:
         for file in generation_script.files:
             file = root / file
@@ -240,6 +242,7 @@ def check_generated_files(generation_scripts: List[GenerationScript], root: Path
                 # there's nothing to compare to, or clean up.
                 continue
             if not filecmp.cmp(file, bak_file):
+                ok = False
                 ref_file = file.with_name(file.name + ".ref")
                 ref_file = root / ref_file
                 if ref_file.exists():
@@ -248,8 +251,9 @@ def check_generated_files(generation_scripts: List[GenerationScript], root: Path
                 print(f"Generated file {file} not identical to the reference one {ref_file}.")
             file.unlink()
             bak_file.rename(file)
+    return ok
 
-def main():
+def main() -> int:
     """
     Main function of this program
     """
@@ -280,10 +284,13 @@ def main():
         files = get_generated_files(generation_scripts)
         for file in files:
             print(str(file))
+        return 0
     elif args.check:
-        check_generated_files(generation_scripts, Path(args.root or "."))
+        ok = check_generated_files(generation_scripts, Path(args.root or "."))
+        return 0 if ok else 1
     else:
         make_generated_files(generation_scripts)
+        return 0 # Any error causes an exception
 
 if __name__ == "__main__":
     sys.exit(main())