diff --git a/src/libexpr/include/nix/expr/eval.hh b/src/libexpr/include/nix/expr/eval.hh
index 4b294ad9a..57f0f3f9d 100644
--- a/src/libexpr/include/nix/expr/eval.hh
+++ b/src/libexpr/include/nix/expr/eval.hh
@@ -431,7 +431,7 @@ private:
      * Associate source positions of certain AST nodes with their preceding doc comment, if they have one.
      * Grouped by file.
      */
-    boost::unordered_flat_map<SourcePath, DocCommentMap, std::hash<SourcePath>> positionToDocComment;
+    boost::unordered_flat_map<SourcePath, DocCommentMap> positionToDocComment;
 
     LookupPath lookupPath;
 
diff --git a/src/libfetchers/filtering-source-accessor.cc b/src/libfetchers/filtering-source-accessor.cc
index d0991ae23..a99ecacef 100644
--- a/src/libfetchers/filtering-source-accessor.cc
+++ b/src/libfetchers/filtering-source-accessor.cc
@@ -59,12 +59,12 @@ void FilteringSourceAccessor::checkAccess(const CanonPath & path)
 struct AllowListSourceAccessorImpl : AllowListSourceAccessor
 {
     std::set<CanonPath> allowedPrefixes;
-    boost::unordered_flat_set<CanonPath, std::hash<CanonPath>> allowedPaths;
+    boost::unordered_flat_set<CanonPath> allowedPaths;
 
     AllowListSourceAccessorImpl(
         ref<SourceAccessor> next,
         std::set<CanonPath> && allowedPrefixes,
-        boost::unordered_flat_set<CanonPath, std::hash<CanonPath>> && allowedPaths,
+        boost::unordered_flat_set<CanonPath> && allowedPaths,
         MakeNotAllowedError && makeNotAllowedError)
         : AllowListSourceAccessor(SourcePath(next), std::move(makeNotAllowedError))
         , allowedPrefixes(std::move(allowedPrefixes))
@@ -86,7 +86,7 @@ struct AllowListSourceAccessorImpl : AllowListSourceAccessor
 ref<AllowListSourceAccessor> AllowListSourceAccessor::create(
     ref<SourceAccessor> next,
     std::set<CanonPath> && allowedPrefixes,
-    boost::unordered_flat_set<CanonPath, std::hash<CanonPath>> && allowedPaths,
+    boost::unordered_flat_set<CanonPath> && allowedPaths,
     MakeNotAllowedError && makeNotAllowedError)
 {
     return make_ref<AllowListSourceAccessorImpl>(
diff --git a/src/libfetchers/git-utils.cc b/src/libfetchers/git-utils.cc
index 4ed94a4ed..a3652e522 100644
--- a/src/libfetchers/git-utils.cc
+++ b/src/libfetchers/git-utils.cc
@@ -817,7 +817,7 @@ struct GitSourceAccessor : SourceAccessor
         return toHash(*git_tree_entry_id(entry));
     }
 
-    boost::unordered_flat_map<CanonPath, TreeEntry, std::hash<CanonPath>> lookupCache;
+    boost::unordered_flat_map<CanonPath, TreeEntry> lookupCache;
 
     /* Recursively look up 'path' relative to the root. */
     git_tree_entry * lookup(State & state, const CanonPath & path)
@@ -1254,7 +1254,7 @@ GitRepoImpl::getAccessor(const WorkdirInfo & wd, bool exportIgnore, MakeNotAllow
                                            makeFSSourceAccessor(path),
                                            std::set<CanonPath>{wd.files},
                                            // Always allow access to the root, but not its children.
-                                           boost::unordered_flat_set<CanonPath, std::hash<CanonPath>>{CanonPath::root},
+                                           boost::unordered_flat_set<CanonPath>{CanonPath::root},
                                            std::move(makeNotAllowedError))
                                            .cast<SourceAccessor>();
     if (exportIgnore)
diff --git a/src/libfetchers/include/nix/fetchers/filtering-source-accessor.hh b/src/libfetchers/include/nix/fetchers/filtering-source-accessor.hh
index 1d4028be5..f8a57bfb3 100644
--- a/src/libfetchers/include/nix/fetchers/filtering-source-accessor.hh
+++ b/src/libfetchers/include/nix/fetchers/filtering-source-accessor.hh
@@ -72,7 +72,7 @@ struct AllowListSourceAccessor : public FilteringSourceAccessor
     static ref<AllowListSourceAccessor> create(
         ref<SourceAccessor> next,
         std::set<CanonPath> && allowedPrefixes,
-        boost::unordered_flat_set<CanonPath, std::hash<CanonPath>> && allowedPaths,
+        boost::unordered_flat_set<CanonPath> && allowedPaths,
         MakeNotAllowedError && makeNotAllowedError);
 
     using FilteringSourceAccessor::FilteringSourceAccessor;