diff --git a/Cargo.lock b/Cargo.lock
index db7cda10ad..e805011655 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1849,6 +1849,7 @@ checksum = "62f822373a4fe84d4bb149bf54e584a7f4abec90e072ed49cda0edea5b95471f"
 dependencies = [
  "equivalent",
  "hashbrown 0.15.2",
+ "serde",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 3f6b77768a..7d5c9011c1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -67,7 +67,7 @@ glob = "0.3.1"
 hashbrown = { version = "0.15.2", default-features = false, features = ["inline-more"] }
 hex = "0.4.3"
 ignore = "0.4.23"
-indexmap = "2.7.0"
+indexmap = { version = "2.7.0", features = ["serde"] }
 indoc = "2.0.4"
 insta = { version = "1.41.1", features = ["filters"] }
 itertools = "0.13.0"
diff --git a/cli/src/formatter.rs b/cli/src/formatter.rs
index f63bdab014..8213879401 100644
--- a/cli/src/formatter.rs
+++ b/cli/src/formatter.rs
@@ -709,6 +709,7 @@ mod tests {
     use std::error::Error as _;
     use std::str;
 
+    use indexmap::IndexMap;
     use indoc::indoc;
     use jj_lib::config::ConfigLayer;
     use jj_lib::config::ConfigSource;
@@ -774,11 +775,10 @@ mod tests {
             bright-cyan = 'bright cyan'
             bright-white = 'bright white'
         "});
-        // TODO: migrate off config::Config and switch to IndexMap
-        let colors: HashMap<String, String> = config.get("colors").unwrap();
+        let colors: IndexMap<String, String> = config.get("colors").unwrap();
         let mut output: Vec<u8> = vec![];
         let mut formatter = ColorFormatter::for_config(&mut output, &config, false).unwrap();
-        for (label, color) in colors.iter().sorted() {
+        for (label, color) in &colors {
             formatter.push_label(label).unwrap();
             write!(formatter, " {color} ").unwrap();
             formatter.pop_label().unwrap();
@@ -787,21 +787,21 @@ mod tests {
         drop(formatter);
         insta::assert_snapshot!(String::from_utf8(output).unwrap(), @r"
          black 
+         red 
+         green 
+         yellow 
          blue 
+         magenta 
+         cyan 
+         white 
          bright black 
-         bright blue 
-         bright cyan 
+         bright red 
          bright green 
+         bright yellow 
+         bright blue 
          bright magenta 
-         bright red 
+         bright cyan 
          bright white 
-         bright yellow 
-         cyan 
-         green 
-         magenta 
-         red 
-         white 
-         yellow 
         ");
     }
 
@@ -814,11 +814,10 @@ mod tests {
             white = '#ffffff'
             pastel-blue = '#AFE0D9'
         "});
-        // TODO: migrate off config::Config and switch to IndexMap
-        let colors: HashMap<String, String> = config.get("colors").unwrap();
+        let colors: IndexMap<String, String> = config.get("colors").unwrap();
         let mut output: Vec<u8> = vec![];
         let mut formatter = ColorFormatter::for_config(&mut output, &config, false).unwrap();
-        for label in colors.keys().sorted() {
+        for label in colors.keys() {
             formatter.push_label(&label.replace(' ', "-")).unwrap();
             write!(formatter, " {label} ").unwrap();
             formatter.pop_label().unwrap();
@@ -827,8 +826,8 @@ mod tests {
         drop(formatter);
         insta::assert_snapshot!(String::from_utf8(output).unwrap(), @r"
          black 
-         pastel-blue 
          white 
+         pastel-blue 
         ");
     }