diff --git a/docs/src/worktrees.md b/docs/src/worktrees.md
index 7dd4799..baa1f4b 100644
--- a/docs/src/worktrees.md
+++ b/docs/src/worktrees.md
@@ -259,6 +259,9 @@ persistent_branches = [
 ]
 ```
 
+Note that setting persistent branches will disable any detection of "default"
+branches. The first entry will be considered your repositories' default branch.
+
 ### Converting an existing repository
 
 It is possible to convert an existing directory to a worktree setup, using `grm
diff --git a/e2e_tests/test_worktree_clean.py b/e2e_tests/test_worktree_clean.py
index fa916e1..17f16ce 100644
--- a/e2e_tests/test_worktree_clean.py
+++ b/e2e_tests/test_worktree_clean.py
@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 
+import pytest
+
 from helpers import *
 
 
@@ -139,3 +141,56 @@ def test_worktree_clean_non_git():
         assert cmd.returncode != 0
         assert len(cmd.stdout) == 0
         assert len(cmd.stderr) != 0
+
+
+@pytest.mark.parametrize("configure_default_branch", [True, False])
+@pytest.mark.parametrize("branch_list_empty", [True, False])
+def test_worktree_clean_configured_default_branch(
+    configure_default_branch, branch_list_empty
+):
+    with TempGitRepositoryWorktree() as (base_dir, _commit):
+        if configure_default_branch:
+            with open(os.path.join(base_dir, "grm.toml"), "w") as f:
+                if branch_list_empty:
+                    f.write(
+                        f"""
+                        persistent_branches = []
+                    """
+                    )
+                else:
+                    f.write(
+                        f"""
+                        persistent_branches = [
+                            "mybranch"
+                        ]
+                    """
+                    )
+
+        cmd = grm(["wt", "add", "test"], cwd=base_dir)
+        assert cmd.returncode == 0
+
+        shell(
+            f"""
+            cd {base_dir}
+            (
+                cd ./test
+                touch change
+                git add change
+                git commit -m commit
+            )
+
+            git --git-dir ./.git-main-working-tree worktree add mybranch
+            (
+                cd ./mybranch
+                git merge --no-ff test
+            )
+            git --git-dir ./.git-main-working-tree worktree remove mybranch
+        """
+        )
+
+        cmd = grm(["wt", "clean"], cwd=base_dir)
+        assert cmd.returncode == 0
+        if configure_default_branch and not branch_list_empty:
+            assert "test" not in os.listdir(base_dir)
+        else:
+            assert "test" in os.listdir(base_dir)
diff --git a/src/repo.rs b/src/repo.rs
index b60eb5e..2daba33 100644
--- a/src/repo.rs
+++ b/src/repo.rs
@@ -880,16 +880,29 @@ impl Repo {
             .get_worktrees()
             .map_err(|error| format!("Getting worktrees failed: {}", error))?;
 
-        let default_branch = self
-            .default_branch()
-            .map_err(|error| format!("Failed getting default branch: {}", error))?;
-
-        let default_branch_name = default_branch
-            .name()
-            .map_err(|error| format!("Failed getting default branch name: {}", error))?;
-
         let config = read_worktree_root_config(directory)?;
 
+        let guess_default_branch = || {
+            self.default_branch()
+                .map_err(|_| "Could not determine default branch")?
+                .name()
+                .map_err(|error| format!("Failed getting default branch name: {}", error))
+        };
+
+        let default_branch_name = match &config {
+            None => guess_default_branch()?,
+            Some(config) => match &config.persistent_branches {
+                None => guess_default_branch()?,
+                Some(persistent_branches) => {
+                    if persistent_branches.is_empty() {
+                        guess_default_branch()?
+                    } else {
+                        persistent_branches[0].clone()
+                    }
+                }
+            },
+        };
+
         for worktree in worktrees
             .iter()
             .filter(|worktree| *worktree != &default_branch_name)
@@ -946,13 +959,28 @@ impl Repo {
                     .unwrap(),
             );
 
-            let default_branch = self
-                .default_branch()
-                .map_err(|error| format!("Failed getting default branch: {}", error))?;
+            let config = read_worktree_root_config(directory)?;
 
-            let default_branch_name = default_branch
-                .name()
-                .map_err(|error| format!("Failed getting default branch name: {}", error))?;
+            let guess_default_branch = || {
+                self.default_branch()
+                    .map_err(|error| format!("Failed getting default branch: {}", error))?
+                    .name()
+                    .map_err(|error| format!("Failed getting default branch name: {}", error))
+            };
+
+            let default_branch_name = match &config {
+                None => guess_default_branch()?,
+                Some(config) => match &config.persistent_branches {
+                    None => guess_default_branch()?,
+                    Some(persistent_branches) => {
+                        if persistent_branches.is_empty() {
+                            guess_default_branch()?
+                        } else {
+                            persistent_branches[0].clone()
+                        }
+                    }
+                },
+            };
 
             if dirname == crate::GIT_MAIN_WORKTREE_DIRECTORY {
                 continue;