1 files changed, 15 insertions, 2 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 2c28b5df6d7..a65dbb48b93 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5951,8 +5951,21 @@ mark_object (Lisp_Object arg)
             break;
 
           case PVEC_FRAME:
-            mark_vectorlike (ptr);
-            mark_face_cache (((struct frame *) ptr)->face_cache);
+            {
+              struct frame *f = (struct frame *) ptr;
+
+              mark_vectorlike (ptr);
+              mark_face_cache (f->face_cache);
+#ifdef HAVE_WINDOW_SYSTEM
+              if (FRAME_WINDOW_P (f) && FRAME_X_OUTPUT (f))
+                {
+                  struct font *font = FRAME_FONT (f);
+
+                  if (font && !VECTOR_MARKED_P (font))
+                    mark_vectorlike ((struct Lisp_Vector *) font);
+                }
+#endif
+            }
             break;
 
           case PVEC_WINDOW: