diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index cd7039025..bfae34a48 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -22,7 +22,7 @@ void emitTreeAttrs(
 {
     assert(input.isLocked());
 
-    auto attrs = state.buildBindings(8);
+    auto attrs = state.buildBindings(10);
 
 
     state.mkStorePathString(tree.storePath, attrs.alloc(state.sOutPath));
@@ -56,6 +56,11 @@ void emitTreeAttrs(
 
     }
 
+    if (auto dirtyRev = fetchers::maybeGetStrAttr(input.attrs, "dirtyRev")) {
+        attrs.alloc("dirtyRev").mkString(*dirtyRev);
+        attrs.alloc("dirtyShortRev").mkString(*fetchers::maybeGetStrAttr(input.attrs, "dirtyShortRev"));
+    }
+
     if (auto lastModified = input.getLastModified()) {
         attrs.alloc("lastModified").mkInt(*lastModified);
         attrs.alloc("lastModifiedDate").mkString(
diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 47282f6c4..be5842d53 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -243,6 +243,13 @@ std::pair<StorePath, Input> fetchFromWorkdir(ref<Store> store, Input & input, co
         "lastModified",
         workdirInfo.hasHead ? std::stoull(runProgram("git", true, { "-C", actualPath, "--git-dir", gitDir, "log", "-1", "--format=%ct", "--no-show-signature", "HEAD" })) : 0);
 
+    if (workdirInfo.hasHead) {
+        input.attrs.insert_or_assign("dirtyRev", chomp(
+            runProgram("git", true, { "-C", actualPath, "--git-dir", gitDir, "rev-parse", "--verify", "HEAD" })) + "-dirty");
+        input.attrs.insert_or_assign("dirtyShortRev", chomp(
+            runProgram("git", true, { "-C", actualPath, "--git-dir", gitDir, "rev-parse", "--verify", "--short", "HEAD" })) + "-dirty");
+    }
+
     return {std::move(storePath), input};
 }
 }  // end namespace
@@ -283,7 +290,7 @@ struct GitInputScheme : InputScheme
         if (maybeGetStrAttr(attrs, "type") != "git") return {};
 
         for (auto & [name, value] : attrs)
-            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "shallow" && name != "submodules" && name != "lastModified" && name != "revCount" && name != "narHash" && name != "allRefs" && name != "name")
+            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "shallow" && name != "submodules" && name != "lastModified" && name != "revCount" && name != "narHash" && name != "allRefs" && name != "name" && name != "dirtyRev" && name != "dirtyShortRev")
                 throw Error("unsupported Git input attribute '%s'", name);
 
         parseURL(getStrAttr(attrs, "url"));
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 1eea52e15..8d39de389 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -179,6 +179,8 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
             j["locked"] = fetchers::attrsToJSON(flake.lockedRef.toAttrs());
             if (auto rev = flake.lockedRef.input.getRev())
                 j["revision"] = rev->to_string(Base16, false);
+            if (auto dirtyRev = fetchers::maybeGetStrAttr(flake.lockedRef.toAttrs(), "dirtyRev"))
+                j["dirtyRevision"] = *dirtyRev;
             if (auto revCount = flake.lockedRef.input.getRevCount())
                 j["revCount"] = *revCount;
             if (auto lastModified = flake.lockedRef.input.getLastModified())
@@ -204,6 +206,10 @@ struct CmdFlakeMetadata : FlakeCommand, MixJSON
                 logger->cout(
                     ANSI_BOLD "Revision:" ANSI_NORMAL "      %s",
                     rev->to_string(Base16, false));
+            if (auto dirtyRev = fetchers::maybeGetStrAttr(flake.lockedRef.toAttrs(), "dirtyRev"))
+                logger->cout(
+                    ANSI_BOLD "Revision:" ANSI_NORMAL "      %s",
+                    *dirtyRev);
             if (auto revCount = flake.lockedRef.input.getRevCount())
                 logger->cout(
                     ANSI_BOLD "Revisions:" ANSI_NORMAL "     %s",
diff --git a/tests/fetchGit.sh b/tests/fetchGit.sh
index e2ccb0e97..418b4f63f 100644
--- a/tests/fetchGit.sh
+++ b/tests/fetchGit.sh
@@ -105,6 +105,8 @@ path2=$(nix eval --impure --raw --expr "(builtins.fetchGit $repo).outPath")
 [[ $(cat $path2/dir1/foo) = foo ]]
 
 [[ $(nix eval --impure --raw --expr "(builtins.fetchGit $repo).rev") = 0000000000000000000000000000000000000000 ]]
+[[ $(nix eval --impure --raw --expr "(builtins.fetchGit $repo).dirtyRev") = "${rev2}-dirty" ]]
+[[ $(nix eval --impure --raw --expr "(builtins.fetchGit $repo).dirtyShortRev") = "${rev2:0:7}-dirty" ]]
 
 # ... unless we're using an explicit ref or rev.
 path3=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = $repo; ref = \"master\"; }).outPath")
@@ -119,6 +121,10 @@ git -C $repo commit -m 'Bla3' -a
 path4=$(nix eval --impure --refresh --raw --expr "(builtins.fetchGit file://$repo).outPath")
 [[ $path2 = $path4 ]]
 
+[[ $(nix eval --impure --expr "builtins.hasAttr \"rev\" (builtins.fetchGit $repo)") == "true" ]]
+[[ $(nix eval --impure --expr "builtins.hasAttr \"dirtyRev\" (builtins.fetchGit $repo)") == "false" ]]
+[[ $(nix eval --impure --expr "builtins.hasAttr \"dirtyShortRev\" (builtins.fetchGit $repo)") == "false" ]]
+
 status=0
 nix eval --impure --raw --expr "(builtins.fetchGit { url = $repo; rev = \"$rev2\"; narHash = \"sha256-B5yIPHhEm0eysJKEsO7nqxprh9vcblFxpJG11gXJus1=\"; }).outPath" || status=$?
 [[ "$status" = "102" ]]
diff --git a/tests/flakes/flakes.sh b/tests/flakes/flakes.sh
index f2e216435..128f759ea 100644
--- a/tests/flakes/flakes.sh
+++ b/tests/flakes/flakes.sh
@@ -95,11 +95,16 @@ json=$(nix flake metadata flake1 --json | jq .)
 [[ $(echo "$json" | jq -r .lastModified) = $(git -C $flake1Dir log -n1 --format=%ct) ]]
 hash1=$(echo "$json" | jq -r .revision)
 
+echo foo > $flake1Dir/foo
+git -C $flake1Dir add $flake1Dir/foo
+[[ $(nix flake metadata flake1 --json --refresh | jq -r .dirtyRevision) == "$hash1-dirty" ]]
+
 echo -n '# foo' >> $flake1Dir/flake.nix
 flake1OriginalCommit=$(git -C $flake1Dir rev-parse HEAD)
 git -C $flake1Dir commit -a -m 'Foo'
 flake1NewCommit=$(git -C $flake1Dir rev-parse HEAD)
 hash2=$(nix flake metadata flake1 --json --refresh | jq -r .revision)
+[[ $(nix flake metadata flake1 --json --refresh | jq -r .dirtyRevision) == "null" ]]
 [[ $hash1 != $hash2 ]]
 
 # Test 'nix build' on a flake.