diff --git a/crates/typos-cli/tests/cmd/extend-builtin-dict.in/_typos.toml b/crates/typos-cli/tests/cmd/extend-builtin-dict.in/_typos.toml
new file mode 100644
index 0000000..c82050d
--- /dev/null
+++ b/crates/typos-cli/tests/cmd/extend-builtin-dict.in/_typos.toml
@@ -0,0 +1,10 @@
+[type.rust]
+check-filename = false
+
+[default.extend-words]
+foo = "bar"
+
+[files]
+extend-exclude = [
+  "_typos.toml"
+]
diff --git a/crates/typos-cli/tests/cmd/extend-builtin-dict.in/foo.rs b/crates/typos-cli/tests/cmd/extend-builtin-dict.in/foo.rs
new file mode 100644
index 0000000..bcfd16d
--- /dev/null
+++ b/crates/typos-cli/tests/cmd/extend-builtin-dict.in/foo.rs
@@ -0,0 +1 @@
+flate2
diff --git a/crates/typos-cli/tests/cmd/extend-builtin-dict.toml b/crates/typos-cli/tests/cmd/extend-builtin-dict.toml
new file mode 100644
index 0000000..c2cdb00
--- /dev/null
+++ b/crates/typos-cli/tests/cmd/extend-builtin-dict.toml
@@ -0,0 +1,16 @@
+bin.name = "typos"
+args = ""
+status.code = 2
+stdin = '''
+\n\n
+Destory
+'''
+stdout = """
+error: `flate` should be `flat`
+  --> ./foo.rs:1:1
+  |
+1 | flate2
+  | ^^^^^
+  |
+"""
+stderr = ""