diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index f255f99e2..c752eeedc 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -280,11 +280,13 @@ static std::string diffLockFiles(const LockedInputs & oldLocks, const LockedInpu
             res += fmt("  removed '%s'\n", concatStringsSep("/", i->first));
             ++i;
         } else {
-            if (!(i->second->ref == j->second->ref))
+            if (!(i->second->ref == j->second->ref)) {
+                assert(i->second->ref.to_string() != j->second->ref.to_string());
                 res += fmt("  updated '%s': '%s' -> '%s'\n",
                     concatStringsSep("/", i->first),
                     i->second->ref,
                     j->second->ref);
+            }
             ++i;
             ++j;
         }
diff --git a/src/libstore/fetchers/git.cc b/src/libstore/fetchers/git.cc
index 16bbcd285..1350c5754 100644
--- a/src/libstore/fetchers/git.cc
+++ b/src/libstore/fetchers/git.cc
@@ -83,7 +83,7 @@ struct GitInput : Input
         auto other2 = dynamic_cast<const GitInput *>(&other);
         return
             other2
-            && url.url == other2->url.url
+            && url == other2->url
             && rev == other2->rev
             && ref == other2->ref;
     }
@@ -361,6 +361,8 @@ struct GitInputScheme : InputScheme
 
         auto input = std::make_unique<GitInput>(url);
 
+        input->url.query.clear();
+
         for (auto &[name, value] : url.query) {
             if (name == "rev") {
                 if (!std::regex_match(value, revRegex))
@@ -372,6 +374,7 @@ struct GitInputScheme : InputScheme
                     throw BadURL("Git URL '%s' contains an invalid branch/tag name", url.url);
                 input->ref = value;
             }
+            else input->url.query.insert_or_assign(name, value);
         }
 
         return input;
diff --git a/src/libstore/fetchers/mercurial.cc b/src/libstore/fetchers/mercurial.cc
index e6f252700..e012f98fc 100644
--- a/src/libstore/fetchers/mercurial.cc
+++ b/src/libstore/fetchers/mercurial.cc
@@ -29,7 +29,7 @@ struct MercurialInput : Input
         auto other2 = dynamic_cast<const MercurialInput *>(&other);
         return
             other2
-            && url.url == other2->url.url
+            && url == other2->url
             && rev == other2->rev
             && ref == other2->ref;
     }
@@ -255,6 +255,8 @@ struct MercurialInputScheme : InputScheme
 
         auto input = std::make_unique<MercurialInput>(url);
 
+        input->url.query.clear();
+
         for (auto &[name, value] : url.query) {
             if (name == "rev") {
                 if (!std::regex_match(value, revRegex))
@@ -266,6 +268,7 @@ struct MercurialInputScheme : InputScheme
                     throw BadURL("Mercurial URL '%s' contains an invalid branch/tag name", url.url);
                 input->ref = value;
             }
+            else input->url.query.insert_or_assign(name, value);
         }
 
         return input;
diff --git a/src/libstore/fetchers/parse.cc b/src/libstore/fetchers/parse.cc
index 88c2844d0..dc1b3efe6 100644
--- a/src/libstore/fetchers/parse.cc
+++ b/src/libstore/fetchers/parse.cc
@@ -127,4 +127,14 @@ std::string ParsedURL::to_string() const
         + (fragment.empty() ? "" : "#" + percentEncode(fragment));
 }
 
+bool ParsedURL::operator ==(const ParsedURL & other) const
+{
+    return
+        scheme == other.scheme
+        && authority == other.authority
+        && path == other.path
+        && query == other.query
+        && fragment == other.fragment;
+}
+
 }
diff --git a/src/libstore/fetchers/parse.hh b/src/libstore/fetchers/parse.hh
index 22cc57816..45d5182b0 100644
--- a/src/libstore/fetchers/parse.hh
+++ b/src/libstore/fetchers/parse.hh
@@ -15,6 +15,8 @@ struct ParsedURL
     std::string fragment;
 
     std::string to_string() const;
+
+    bool operator ==(const ParsedURL & other) const;
 };
 
 MakeError(BadURL, Error);