diff --git a/lib/src/local_working_copy.rs b/lib/src/local_working_copy.rs
index 3951c3ad3..bc7c34bcc 100644
--- a/lib/src/local_working_copy.rs
+++ b/lib/src/local_working_copy.rs
@@ -15,7 +15,7 @@
 #![allow(missing_docs)]
 
 use std::any::Any;
-use std::collections::{BTreeMap, HashMap, HashSet};
+use std::collections::{BTreeMap, HashSet};
 use std::error::Error;
 use std::fs;
 use std::fs::{File, Metadata, OpenOptions};
@@ -195,12 +195,12 @@ fn file_state_to_proto(file_state: &FileState) -> crate::protos::working_copy::F
 }
 
 fn file_states_from_proto(
-    proto: &HashMap<String, crate::protos::working_copy::FileState>,
+    proto: &[crate::protos::working_copy::FileStateEntry],
 ) -> BTreeMap<RepoPath, FileState> {
     let mut file_states = BTreeMap::new();
-    for (path_str, proto_file_state) in proto {
-        let path = RepoPath::from_internal_string(path_str);
-        file_states.insert(path, file_state_from_proto(proto_file_state));
+    for entry in proto {
+        let path = RepoPath::from_internal_string(&entry.path);
+        file_states.insert(path, file_state_from_proto(entry.state.as_ref().unwrap()));
     }
     file_states
 }
@@ -465,12 +465,16 @@ impl TreeState {
             }
         }
 
-        for (file, file_state) in &self.file_states {
-            proto.file_states.insert(
-                file.to_internal_file_string(),
-                file_state_to_proto(file_state),
-            );
-        }
+        proto.file_states = self
+            .file_states
+            .iter()
+            .map(
+                |(path, state)| crate::protos::working_copy::FileStateEntry {
+                    path: path.to_internal_file_string(),
+                    state: Some(file_state_to_proto(state)),
+                },
+            )
+            .collect();
         let mut sparse_patterns = crate::protos::working_copy::SparsePatterns::default();
         for path in &self.sparse_patterns {
             sparse_patterns
diff --git a/lib/src/protos/working_copy.proto b/lib/src/protos/working_copy.proto
index 3220e9ea2..1fc658b48 100644
--- a/lib/src/protos/working_copy.proto
+++ b/lib/src/protos/working_copy.proto
@@ -32,6 +32,11 @@ message FileState {
   bytes conflict_id = 4 [deprecated = true];
 }
 
+message FileStateEntry {
+  string path = 1;
+  FileState state = 2;
+}
+
 message SparsePatterns {
   repeated string prefixes = 1;
 }
@@ -41,7 +46,7 @@ message TreeState {
   // Alternating positive and negative terms if there's a conflict, otherwise a
   // single (positive) value
   repeated bytes tree_ids = 5;
-  map<string, FileState> file_states = 2;
+  repeated FileStateEntry file_states = 2;
   SparsePatterns sparse_patterns = 3;
   WatchmanClock watchman_clock = 4;
 }
diff --git a/lib/src/protos/working_copy.rs b/lib/src/protos/working_copy.rs
index 30d7b82f7..7d3016545 100644
--- a/lib/src/protos/working_copy.rs
+++ b/lib/src/protos/working_copy.rs
@@ -14,6 +14,14 @@ pub struct FileState {
 }
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
+pub struct FileStateEntry {
+    #[prost(string, tag = "1")]
+    pub path: ::prost::alloc::string::String,
+    #[prost(message, optional, tag = "2")]
+    pub state: ::core::option::Option<FileState>,
+}
+#[allow(clippy::derive_partial_eq_without_eq)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct SparsePatterns {
     #[prost(string, repeated, tag = "1")]
     pub prefixes: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
@@ -27,11 +35,8 @@ pub struct TreeState {
     /// single (positive) value
     #[prost(bytes = "vec", repeated, tag = "5")]
     pub tree_ids: ::prost::alloc::vec::Vec<::prost::alloc::vec::Vec<u8>>,
-    #[prost(map = "string, message", tag = "2")]
-    pub file_states: ::std::collections::HashMap<
-        ::prost::alloc::string::String,
-        FileState,
-    >,
+    #[prost(message, repeated, tag = "2")]
+    pub file_states: ::prost::alloc::vec::Vec<FileStateEntry>,
     #[prost(message, optional, tag = "3")]
     pub sparse_patterns: ::core::option::Option<SparsePatterns>,
     #[prost(message, optional, tag = "4")]