diff --git a/server/refreshhandlers.go b/server/refreshhandlers.go
index de8d9b7b..8ea5a8b0 100644
--- a/server/refreshhandlers.go
+++ b/server/refreshhandlers.go
@@ -232,7 +232,9 @@ func (s *Server) updateOfflineSession(ctx context.Context, refresh *storage.Refr
 	return nil
 }
 
-// updateRefreshToken updates refresh token and offline session in the storage
+// updateRefreshToken updates refresh token and offline session in the storage.
+// Connector refresh is guarded by a per-refresh-ID mutex so only one concurrent
+// caller hits the IdP.
 func (s *Server) updateRefreshToken(ctx context.Context, rCtx *refreshContext) (*internal.RefreshToken, connector.Identity, *refreshError) {
 	var rerr *refreshError
 
@@ -240,7 +242,6 @@ func (s *Server) updateRefreshToken(ctx context.Context, rCtx *refreshContext) (
 		Token:     rCtx.requestToken.Token,
 		RefreshId: rCtx.requestToken.RefreshId,
 	}
-
 	lastUsed := s.now()
 
 	ident := connector.Identity{
@@ -250,6 +251,31 @@ func (s *Server) updateRefreshToken(ctx context.Context, rCtx *refreshContext) (
 		Email:             rCtx.storageToken.Claims.Email,
 		EmailVerified:     rCtx.storageToken.Claims.EmailVerified,
 		Groups:            rCtx.storageToken.Claims.Groups,
+		ConnectorData:     rCtx.connectorData,
+	}
+
+	rotationEnabled := s.refreshTokenPolicy.RotationEnabled()
+	reusingAllowed := s.refreshTokenPolicy.AllowedToReuse(rCtx.storageToken.LastUsed)
+	needConnectorRefresh := rotationEnabled && !reusingAllowed
+
+	if needConnectorRefresh {
+		// Serialize concurrent refreshes for the same refresh ID.
+		lock := s.getRefreshLock(rCtx.storageToken.ID)
+		lock.Lock()
+		s.logger.Debug("Acquired refresh lock", "refreshID", rCtx.storageToken.ID)
+		defer func() {
+			lock.Unlock()
+			s.logger.Debug("Released refresh lock", "refreshID", rCtx.storageToken.ID)
+		}()
+
+		// Double-check if another goroutine already refreshed while we waited:
+		if !s.refreshTokenPolicy.AllowedToReuse(rCtx.storageToken.LastUsed) {
+			var rerr *refreshError
+			ident, rerr = s.refreshWithConnector(ctx, rCtx, ident)
+			if rerr != nil {
+				return nil, ident, rerr
+			}
+		}
 	}
 
 	refreshTokenUpdater := func(old storage.RefreshToken) (storage.RefreshToken, error) {
@@ -293,14 +319,6 @@ func (s *Server) updateRefreshToken(ctx context.Context, rCtx *refreshContext) (
 		// ConnectorData has been moved to OfflineSession
 		old.ConnectorData = nil
 
-		// Call  only once if there is a request which is not in the reuse interval.
-		// This is required to avoid multiple calls to the external IdP for concurrent requests.
-		// Dex will call the connector's Refresh method only once if request is not in reuse interval.
-		ident, rerr = s.refreshWithConnector(ctx, rCtx, ident)
-		if rerr != nil {
-			return old, rerr
-		}
-
 		// Update the claims of the refresh token.
 		//
 		// UserID intentionally ignored for now.
diff --git a/server/server.go b/server/server.go
index 70e8ae75..c2425053 100644
--- a/server/server.go
+++ b/server/server.go
@@ -198,6 +198,8 @@ type Server struct {
 	deviceRequestsValidFor time.Duration
 
 	refreshTokenPolicy *RefreshTokenPolicy
+	// mutex to refresh the same token only once for concurrent requests
+	refreshLocks sync.Map
 
 	logger *slog.Logger
 }
@@ -758,6 +760,12 @@ func (s *Server) getConnector(ctx context.Context, id string) (Connector, error)
 	return conn, nil
 }
 
+// getRefreshLock returns a per-refresh-ID mutex.
+func (s *Server) getRefreshLock(refreshID string) *sync.Mutex {
+	m, _ := s.refreshLocks.LoadOrStore(refreshID, &sync.Mutex{})
+	return m.(*sync.Mutex)
+}
+
 type logRequestKey string
 
 const (