diff --git a/CHANGES.md b/CHANGES.md
index ee69eb2..21092e6 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -3,6 +3,7 @@
 Unreleased
 
 - Submit is disabled by default.
+- Error if target and work branch are the same.
 
 ## Version 0.1.0
 
diff --git a/src/modify_repos/script/base.py b/src/modify_repos/script/base.py
index 48dc386..a90f7a2 100644
--- a/src/modify_repos/script/base.py
+++ b/src/modify_repos/script/base.py
@@ -41,7 +41,11 @@ class Script[RepoType: Repo]:
     """
 
     def __init__(self, *, submit: bool = False) -> None:
-        """ """
+        if self.target == self.branch:
+            raise ValueError(
+                "Work branch name must be different than target branch name."
+            )
+
         source_file = inspect.getsourcefile(self.__class__)
 
         if source_file is None:
diff --git a/uv.lock b/uv.lock
index 1008e0f..27d5167 100644
--- a/uv.lock
+++ b/uv.lock
@@ -335,7 +335,7 @@ wheels = [
 
 [[package]]
 name = "modify-repos"
-version = "0.1.0"
+version = "0.1.1.dev0"
 source = { editable = "." }
 dependencies = [
     { name = "click" },