diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 8e87a262192..2e7dfb73c2c 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -1100,7 +1100,7 @@
     }
 
     /// Return all `impl` blocks in the current crate.
-    query all_local_trait_impls(_: ()) -> &'tcx BTreeMap<DefId, Vec<LocalDefId>> {
+    query all_local_trait_impls(_: ()) -> &'tcx rustc_data_structures::fx::FxIndexMap<DefId, Vec<LocalDefId>> {
         desc { "local trait impls" }
     }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 78878487a9b..8eb2793cc34 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -28,7 +28,7 @@
 use crate::ty::util::Discr;
 use rustc_ast as ast;
 use rustc_attr as attr;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
 use rustc_hir as hir;
@@ -43,7 +43,6 @@
 use rustc_target::abi::Align;
 
 use std::cmp::Ordering;
-use std::collections::BTreeMap;
 use std::hash::{Hash, Hasher};
 use std::ops::ControlFlow;
 use std::{fmt, ptr, str};
@@ -136,7 +135,7 @@ pub struct ResolverOutputs {
     /// via `extern crate` item and not `--extern` option or compiler built-in.
     pub extern_prelude: FxHashMap<Symbol, bool>,
     pub main_def: Option<MainDefinition>,
-    pub trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
+    pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
     /// A list of proc macro LocalDefIds, written out in the order in which
     /// they are declared in the static array generated by proc_macro_harness.
     pub proc_macros: Vec<LocalDefId>,
diff --git a/compiler/rustc_middle/src/ty/query.rs b/compiler/rustc_middle/src/ty/query.rs
index 4a38d1c422f..040e642b7b6 100644
--- a/compiler/rustc_middle/src/ty/query.rs
+++ b/compiler/rustc_middle/src/ty/query.rs
@@ -56,7 +56,6 @@
 use rustc_attr as attr;
 use rustc_span::symbol::Symbol;
 use rustc_span::{Span, DUMMY_SP};
-use std::collections::BTreeMap;
 use std::ops::Deref;
 use std::path::PathBuf;
 use std::sync::Arc;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index d5ad95ace97..28f06ed3a26 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -68,7 +68,7 @@
 
 use smallvec::{smallvec, SmallVec};
 use std::cell::{Cell, RefCell};
-use std::collections::{BTreeMap, BTreeSet};
+use std::collections::BTreeSet;
 use std::ops::ControlFlow;
 use std::{cmp, fmt, iter, mem, ptr};
 use tracing::debug;
@@ -1061,7 +1061,7 @@ pub struct Resolver<'a> {
     item_generics_num_lifetimes: FxHashMap<LocalDefId, usize>,
 
     main_def: Option<MainDefinition>,
-    trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
+    trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
     /// A list of proc macro LocalDefIds, written out in the order in which
     /// they are declared in the static array generated by proc_macro_harness.
     proc_macros: Vec<NodeId>,