diff --git a/pkgs/development/compilers/dart/fetch-git-hashes.py b/pkgs/development/compilers/dart/fetch-git-hashes.py
index b2b3f67746db..fdb34830bc12 100755
--- a/pkgs/development/compilers/dart/fetch-git-hashes.py
+++ b/pkgs/development/compilers/dart/fetch-git-hashes.py
@@ -9,7 +9,7 @@ from pathlib import Path
 
 def fetch_git_hash(url: str, rev: str) -> str:
     result = subprocess.run(
-        ["nix-prefetch-git", "--url", url, "--rev", rev],
+        ["nix-prefetch-git", "--fetch-submodules", "--url", url, "--rev", rev],
         capture_output=True,
         text=True,
         check=True,