diff --git a/tools/export/uvision/postbuild.py b/tools/export/uvision/postbuild.py
index 145770f687..2da1c11022 100644
--- a/tools/export/uvision/postbuild.py
+++ b/tools/export/uvision/postbuild.py
@@ -87,7 +87,9 @@ if __name__ == "__main__":
 
     notify = TerminalNotifier()
     restrict_size = export_info_data.get("target", {}).get("restrict_size")
-    merge_region_list(region_list, combined_hex_file, notify, restrict_size)
+    merge_region_list(
+        region_list, combined_hex_file, notify, restrict_size=restrict_size
+    )
 
     update_regions = [
         r for r in region_list if r.name in UPDATE_WHITELIST
@@ -100,6 +102,8 @@ if __name__ == "__main__":
                 generate_update_filename(output_name, None)
             )
         )
-        merge_region_list(update_regions, update_res, notify, restrict_size)
+        merge_region_list(
+            update_regions, update_res, notify, restrict_size=restrict_size
+        )
 
     sys.exit(0)
diff --git a/tools/toolchains/mbed_toolchain.py b/tools/toolchains/mbed_toolchain.py
index c5945a8d1a..4d44b806bc 100755
--- a/tools/toolchains/mbed_toolchain.py
+++ b/tools/toolchains/mbed_toolchain.py
@@ -664,7 +664,8 @@ class mbedToolchain:
                        for r in region_list]
         res = "{}.{}".format(join(self.build_dir, name), ext)
         merge_region_list(
-            region_list, res, self.notify, self.config.target.restrict_size
+            region_list, res, self.notify,
+            restrict_size=self.config.target.restrict_size
         )
         update_regions = [
             r for r in region_list if r.name in UPDATE_WHITELIST
@@ -678,7 +679,7 @@ class mbedToolchain:
                 update_regions,
                 update_res,
                 self.notify,
-                self.config.target.restrict_size
+                restrict_size=self.config.target.restrict_size
             )
             return res, update_res
         else: