diff --git a/mempalace/cli.py b/mempalace/cli.py
index 1b59f0b..803719d 100644
--- a/mempalace/cli.py
+++ b/mempalace/cli.py
@@ -134,7 +134,8 @@ def cmd_split(args):
     import sys
 
     # Rebuild argv for split_mega_files argparse
-    argv = ["--source", args.dir]
+    # Expand ~ and resolve to absolute path so split_mega_files sees a real path
+    argv = ["--source", str(Path(args.dir).expanduser().resolve())]
     if args.output_dir:
         argv += ["--output-dir", args.output_dir]
     if args.dry_run:
diff --git a/mempalace/split_mega_files.py b/mempalace/split_mega_files.py
index 24b5956..f57beca 100644
--- a/mempalace/split_mega_files.py
+++ b/mempalace/split_mega_files.py
@@ -261,7 +261,7 @@ def main():
     )
     args = parser.parse_args()
 
-    src_dir = Path(args.source) if args.source else LUMI_DIR
+    src_dir = Path(args.source).expanduser().resolve() if args.source else LUMI_DIR
     output_dir = args.output_dir or None  # None = same dir as file
 
     if args.file: