diff --git a/Cargo.lock b/Cargo.lock
index a379e4641db..e86f899672b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -646,9 +646,9 @@ checksum = "acbf1af155f9b9ef647e42cdc158db4b64a1b61f743629225fde6f3e0be2a7c7"
 
 [[package]]
 name = "completest"
-version = "0.0.11"
+version = "0.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d5c57cc5ce58820d1da6538531606500422d4c9cbaea47f6a14d9ed96717a8b"
+checksum = "76e97ff3875a8bb8020fa8897bc79583e71258d2e78b033af571606213f90beb"
 dependencies = [
  "ptyprocess",
  "vte 0.11.1",
diff --git a/clap_complete/Cargo.toml b/clap_complete/Cargo.toml
index 3eb2cb5d877..a4c20e47a50 100644
--- a/clap_complete/Cargo.toml
+++ b/clap_complete/Cargo.toml
@@ -43,7 +43,7 @@ unicode-xid = { version = "0.2.2", optional = true }
 snapbox = { version = "0.4.11", features = ["diff", "path", "examples"] }
 # Cutting out `filesystem` feature
 trycmd = { version = "0.14.16", default-features = false, features = ["color-auto", "diff", "examples"] }
-completest = "0.0.11"
+completest = "0.0.12"
 clap = { path = "../", version = "4.0.0", default-features = false, features = ["std", "derive", "help"] }
 
 [[example]]
diff --git a/clap_complete/tests/testsuite/bash.rs b/clap_complete/tests/testsuite/bash.rs
index a29803d7afe..db03d2bbbcb 100644
--- a/clap_complete/tests/testsuite/bash.rs
+++ b/clap_complete/tests/testsuite/bash.rs
@@ -154,7 +154,7 @@ fn complete() {
     }
 
     let term = completest::Term::new();
-    let runtime = common::load_runtime("test", completest::Shell::Bash);
+    let mut runtime = common::load_runtime("test", completest::Shell::Bash);
 
     let input = "test \t\t";
     let expected = r#"%
diff --git a/clap_complete/tests/testsuite/common.rs b/clap_complete/tests/testsuite/common.rs
index e40e57d8881..6a00593ba7b 100644
--- a/clap_complete/tests/testsuite/common.rs
+++ b/clap_complete/tests/testsuite/common.rs
@@ -365,7 +365,7 @@ pub fn register_example(name: &str, shell: completest::Shell) {
     let registration = std::str::from_utf8(&registration.stdout).unwrap();
     assert!(!registration.is_empty());
 
-    let runtime = shell.init(bin_root, scratch_path.to_owned()).unwrap();
+    let mut runtime = shell.init(bin_root, scratch_path.to_owned()).unwrap();
 
     runtime.register(name, registration).unwrap();
 
@@ -408,11 +408,11 @@ impl completest::Runtime for ScratchRuntime {
         self.runtime.home()
     }
 
-    fn register(&self, name: &str, content: &str) -> std::io::Result<()> {
+    fn register(&mut self, name: &str, content: &str) -> std::io::Result<()> {
         self.runtime.register(name, content)
     }
 
-    fn complete(&self, input: &str, term: &completest::Term) -> std::io::Result<String> {
+    fn complete(&mut self, input: &str, term: &completest::Term) -> std::io::Result<String> {
         let output = self.runtime.complete(input, term)?;
         // HACK: elvish prints and clears this message when a completer takes too long which is
         // dependent on a lot of factors, making this show up or no sometimes (especially if we
diff --git a/clap_complete/tests/testsuite/elvish.rs b/clap_complete/tests/testsuite/elvish.rs
index 731df02405b..788189f964a 100644
--- a/clap_complete/tests/testsuite/elvish.rs
+++ b/clap_complete/tests/testsuite/elvish.rs
@@ -138,7 +138,7 @@ fn complete() {
     }
 
     let term = completest::Term::new();
-    let runtime = common::load_runtime("test", completest::Shell::Elvish);
+    let mut runtime = common::load_runtime("test", completest::Shell::Elvish);
 
     let input = "test \t";
     let expected = r#"% test --generate
diff --git a/clap_complete/tests/testsuite/fish.rs b/clap_complete/tests/testsuite/fish.rs
index 287ae263aa5..7e1b598db74 100644
--- a/clap_complete/tests/testsuite/fish.rs
+++ b/clap_complete/tests/testsuite/fish.rs
@@ -138,7 +138,7 @@ fn complete() {
     }
 
     let term = completest::Term::new();
-    let runtime = common::load_runtime("test", completest::Shell::Fish);
+    let mut runtime = common::load_runtime("test", completest::Shell::Fish);
 
     let input = "test \t";
     let expected = r#"% test
diff --git a/clap_complete/tests/testsuite/zsh.rs b/clap_complete/tests/testsuite/zsh.rs
index c6c4f3a59c2..b226025efcb 100644
--- a/clap_complete/tests/testsuite/zsh.rs
+++ b/clap_complete/tests/testsuite/zsh.rs
@@ -138,7 +138,7 @@ fn complete() {
     }
 
     let term = completest::Term::new();
-    let runtime = common::load_runtime("test", completest::Shell::Zsh);
+    let mut runtime = common::load_runtime("test", completest::Shell::Zsh);
 
     let input = "test \t";
     let expected = r#"% test