diff --git a/extmod/modframebuf.c b/extmod/modframebuf.c
index 062a63c3b2..00a48379b6 100644
--- a/extmod/modframebuf.c
+++ b/extmod/modframebuf.c
@@ -237,12 +237,14 @@ STATIC mp_obj_t framebuf_make_new(const mp_obj_type_t *type, size_t n_args, size
     switch (o->format) {
         case FRAMEBUF_MVLSB:
         case FRAMEBUF_RGB565:
-        case FRAMEBUF_GS4_HMSB:
             break;
         case FRAMEBUF_MHLSB:
         case FRAMEBUF_MHMSB:
             o->stride = (o->stride + 7) & ~7;
             break;
+        case FRAMEBUF_GS4_HMSB:
+            o->stride = (o->stride + 1) & ~1;
+            break;
         default:
             mp_raise_ValueError("invalid format");
     }