diff --git a/t/testenv.sh b/t/testenv.sh
index 30fbe9228d..0018a35958 100644
--- a/t/testenv.sh
+++ b/t/testenv.sh
@@ -77,7 +77,12 @@ BINPATH="$ROOTDIR/bin"
 PATH="$BINPATH:$PATH"
 
 # Always provide a test dir outside our git repo if not specified
-TEMPDIR_PREFIX="git-lfs_TEMP.XXXXXX"
+if [ "$IS_MAC" -eq 1 ]; then
+  TEMPDIR_PREFIX="git-lfs_TEMP"
+else
+  TEMPDIR_PREFIX="git-lfs_TEMP.XXXXXX"
+fi
+
 if [ -z "$GIT_LFS_TEST_DIR" ]; then
     GIT_LFS_TEST_DIR=$(mktemp -d -t "$TEMPDIR_PREFIX")
     GIT_LFS_TEST_DIR=$(resolve_symlink $GIT_LFS_TEST_DIR)