diff --git a/services/pull/merge.go b/services/pull/merge.go
index 4925302797..1137296cae 100644
--- a/services/pull/merge.go
+++ b/services/pull/merge.go
@@ -436,20 +436,24 @@ func doMergeAndPush(ctx context.Context, pr *issues_model.PullRequest, doer *use
 
 func commitAndSignNoAuthor(ctx *mergeContext, message string) error {
 	cmdCommit := gitcmd.NewCommand("commit").AddOptionFormat("--message=%s", message)
-	if ctx.signKey == nil {
-		cmdCommit.AddArguments("--no-gpg-sign")
-	} else {
-		if ctx.signKey.Format != "" {
-			cmdCommit.AddConfig("gpg.format", ctx.signKey.Format)
-		}
-		cmdCommit.AddOptionFormat("-S%s", ctx.signKey.KeyID)
-	}
+	addCommitSigningOptions(cmdCommit, ctx.signKey)
 	if err := ctx.PrepareGitCmd(cmdCommit).RunWithStderr(ctx); err != nil {
 		return fmt.Errorf("git commit %v: %w\n%s", ctx.pr, err, ctx.outbuf.String())
 	}
 	return nil
 }
 
+func addCommitSigningOptions(cmd *gitcmd.Command, signKey *git.SigningKey) {
+	if signKey == nil {
+		cmd.AddArguments("--no-gpg-sign")
+		return
+	}
+	if signKey.Format != "" {
+		cmd.AddConfig("gpg.format", signKey.Format)
+	}
+	cmd.AddOptionFormat("--gpg-sign=%s", signKey.KeyID)
+}
+
 // ErrMergeConflicts represents an error if merging fails with a conflict
 type ErrMergeConflicts struct {
 	Style  repo_model.MergeStyle
diff --git a/services/pull/merge_prepare.go b/services/pull/merge_prepare.go
index 1131a23d85..c23bfdc7f6 100644
--- a/services/pull/merge_prepare.go
+++ b/services/pull/merge_prepare.go
@@ -260,7 +260,9 @@ func rebaseTrackingOnToBase(ctx *mergeContext, mergeStyle repo_model.MergeStyle)
 	ctx.outbuf.Reset()
 
 	// Rebase before merging
-	if err := ctx.PrepareGitCmd(gitcmd.NewCommand("rebase").AddDynamicArguments(tmpRepoBaseBranch)).
+	cmdRebase := gitcmd.NewCommand("rebase").AddDynamicArguments(tmpRepoBaseBranch)
+	addCommitSigningOptions(cmdRebase, ctx.signKey)
+	if err := ctx.PrepareGitCmd(cmdRebase).
 		RunWithStderr(ctx); err != nil {
 		// Rebase will leave a REBASE_HEAD file in .git if there is a conflict
 		if _, statErr := os.Stat(filepath.Join(ctx.tmpBasePath, ".git", "REBASE_HEAD")); statErr == nil {
diff --git a/services/pull/merge_rebase.go b/services/pull/merge_rebase.go
index 9dbe67a6c6..0224f7f1bd 100644
--- a/services/pull/merge_rebase.go
+++ b/services/pull/merge_rebase.go
@@ -74,10 +74,10 @@ func doMergeRebaseFastForward(ctx *mergeContext) error {
 	}
 
 	if newMessage != "" {
-		if err := gitcmd.NewCommand("commit", "--amend").
-			AddOptionFormat("--message=%s", newMessage).
-			WithDir(ctx.tmpBasePath).
-			Run(ctx); err != nil {
+		cmdCommit := gitcmd.NewCommand("commit", "--amend").
+			AddOptionFormat("--message=%s", newMessage)
+		addCommitSigningOptions(cmdCommit, ctx.signKey)
+		if err := cmdCommit.WithDir(ctx.tmpBasePath).Run(ctx); err != nil {
 			log.Error("Unable to amend commit message: %v", err)
 			return err
 		}
diff --git a/services/pull/merge_squash.go b/services/pull/merge_squash.go
index 6c101c8e89..0f716f4d77 100644
--- a/services/pull/merge_squash.go
+++ b/services/pull/merge_squash.go
@@ -73,14 +73,7 @@ func doMergeStyleSquash(ctx *mergeContext, message string) error {
 		AddOptionFormat("--author='%s <%s>'", sig.Name, sig.Email).
 		AddOptionFormat("--message=%s", message).
 		AddArguments("--allow-empty")
-	if ctx.signKey == nil {
-		cmdCommit.AddArguments("--no-gpg-sign")
-	} else {
-		if ctx.signKey.Format != "" {
-			cmdCommit.AddConfig("gpg.format", ctx.signKey.Format)
-		}
-		cmdCommit.AddOptionFormat("-S%s", ctx.signKey.KeyID)
-	}
+	addCommitSigningOptions(cmdCommit, ctx.signKey)
 	if err := ctx.PrepareGitCmd(cmdCommit).RunWithStderr(ctx); err != nil {
 		log.Error("git commit %-v: %v\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), err.Stderr())
 		return fmt.Errorf("git commit [%s:%s -> %s:%s]: %w\n%s\n%s", ctx.pr.HeadRepo.FullName(), ctx.pr.HeadBranch, ctx.pr.BaseRepo.FullName(), ctx.pr.BaseBranch, err, ctx.outbuf.String(), err.Stderr())
diff --git a/tests/integration/gpg_ssh_git_test.go b/tests/integration/gpg_ssh_git_test.go
index 56f9f87783..a95ff77dab 100644
--- a/tests/integration/gpg_ssh_git_test.go
+++ b/tests/integration/gpg_ssh_git_test.go
@@ -9,6 +9,7 @@ import (
 	"encoding/base64"
 	"encoding/pem"
 	"fmt"
+	"net/http"
 	"net/url"
 	"os"
 	"testing"
@@ -255,6 +256,52 @@ func testGitSigning(t *testing.T) {
 				assert.True(t, branch.Commit.Verification.Verified)
 			}))
 		})
+
+		setting.Repository.Signing.Merges = []string{"commitssigned"}
+		setting.Repository.Signing.CRUDActions = []string{"always"}
+		t.Run("UpdateRebaseSigned", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			testCtx := NewAPITestContext(t, username, "update-rebase-signed", auth_model.AccessTokenScopeWriteRepository, auth_model.AccessTokenScopeWriteUser)
+			t.Run("CreateRepository", doAPICreateRepository(testCtx, false))
+
+			var repoID int64
+			t.Run("GetRepository", doAPIGetRepository(testCtx, func(t *testing.T, repo api.Repository) {
+				repoID = repo.ID
+			}))
+			enableRepoAllowUpdateWithRebase(t, repoID, true)
+
+			t.Run("CreateFeatureCommit", crudActionCreateFile(
+				t, testCtx, user, "master", "feature", "signed-feature.txt"))
+			pr, err := doAPICreatePullRequest(testCtx, testCtx.Username, testCtx.Reponame, "master", "feature")(t)
+			require.NoError(t, err)
+
+			content := base64.StdEncoding.EncodeToString([]byte("update base"))
+			t.Run("UpdateBase", doAPICreateFile(testCtx, "signed-base.txt", &api.CreateFileOptions{
+				FileOptions: api.FileOptions{
+					BranchName: "master",
+					Message:    "update base",
+					Author: api.Identity{
+						Name:  user.FullName,
+						Email: user.Email,
+					},
+					Committer: api.Identity{
+						Name:  user.FullName,
+						Email: user.Email,
+					},
+				},
+				ContentBase64: content,
+			}))
+
+			req := NewRequestf(t, "POST", "/api/v1/repos/%s/%s/pulls/%d/update?style=rebase", testCtx.Username, testCtx.Reponame, pr.Index).
+				AddTokenAuth(testCtx.Token)
+			testCtx.Session.MakeRequest(t, req, http.StatusOK)
+
+			t.Run("CheckFeatureBranchSigned", doAPIGetBranch(testCtx, "feature", func(t *testing.T, branch api.Branch) {
+				require.NotNil(t, branch.Commit)
+				require.NotNil(t, branch.Commit.Verification)
+				assert.True(t, branch.Commit.Verification.Verified)
+			}))
+		})
 	})
 }