diff --git a/ui2abc/gn/command/gen_sdk.py b/ui2abc/gn/command/gen_sdk.py
index f9bb97ea23a044fa88d0540bf98f23e02d1c05fb..9e88e15981de5c044e5e92de181cae92c118ce00 100755
--- a/ui2abc/gn/command/gen_sdk.py
+++ b/ui2abc/gn/command/gen_sdk.py
@@ -28,9 +28,6 @@ def get_compiler_type(os, cpu):
         return 'mingw_x86_64'
     return 'clang_x64'
 
-def replace_out_root(value, out_root, compiler_type):
-    """Replace $out_root in the string with the actual value."""
-    return value.replace("$out_root", out_root).replace("$compiler_type", compiler_type)
 
 def validate_out_root(out_root, compiler_type):
     head_out_root, tail_out_root = os.path.split(out_root)
@@ -38,18 +35,18 @@ def validate_out_root(out_root, compiler_type):
         return head_out_root
     return out_root
 
+def apply_substitutions(targets, substitutions):
+    # Replace $out_root et al
+    for i in range(len(targets)):
+        for key, val in substitutions.items():
+            targets[i] = targets[i].replace(key, val)
+    return targets
 
-def copy_files(config, src_base, dist_base, out_root, compiler_type, substitutions):
+
+def copy_files(config, src_base, dist_base, substitutions):
     """Copy files or directories based on the configuration."""
     for mapping in config['file_mappings']:
-        # Replace $out_root
-        source = replace_out_root(mapping['source'], out_root, compiler_type)
-        destination = replace_out_root(mapping['destination'], out_root, compiler_type)
-
-        if substitutions:
-            for key, val in substitutions.items():
-                source = source.replace(key, val)
-                destination = destination.replace(key, val)
+        source, destination = apply_substitutions([mapping[key] for key in ['source', 'destination']], substitutions)
 
         # Build full paths
         source = os.path.join(src_base, source)
@@ -95,18 +92,18 @@ def main():
     config = load_config(args.config)
 
     compiler_type = get_compiler_type(args.current_os, args.current_cpu)
-
     out_root = validate_out_root(args.out_root, compiler_type)
 
-    substitutions = config.get('substitutions')
+    substitutions = {"$out_root": out_root, "$compiler_type": compiler_type}
 
-    if substitutions:
-        substitutions = substitutions.get(args.current_os)
-        if not substitutions:
+    cfg_subst = config.get('substitutions')
+    if cfg_subst:
+        if args.current_os not in cfg_subst:
             raise Exception(f'Substitutions not found for current_os "{args.current_os}".')
+        substitutions.update(cfg_subst.get(args.current_os))
 
     # Copy files or directories
-    copy_files(config, args.src, args.dist, out_root, compiler_type, substitutions)
+    copy_files(config, args.src, args.dist, substitutions)
 
     # Create package.json to pass SDK validation
     content = """{