diff --git a/src/panfrost/vulkan/panvk_vX_cs.c b/src/panfrost/vulkan/panvk_vX_cs.c
index b270ff6fb7e..0f25b66242f 100644
--- a/src/panfrost/vulkan/panvk_vX_cs.c
+++ b/src/panfrost/vulkan/panvk_vX_cs.c
@@ -116,7 +116,13 @@ panvk_varying_hw_format(const struct panvk_device *dev,
              panfrost_get_default_swizzle(4);
    default:
       assert(!panvk_varying_is_builtin(stage, loc));
-      return pdev->formats[varyings->varying[loc].format].hw;
+      if (varyings->varying[loc].format != PIPE_FORMAT_NONE)
+         return pdev->formats[varyings->varying[loc].format].hw;
+#if PAN_ARCH >= 7
+      return (MALI_CONSTANT << 12) | MALI_RGB_COMPONENT_ORDER_0000;
+#else
+      return (MALI_CONSTANT << 12) | PAN_V6_SWIZZLE(0, 0, 0, 0);
+#endif
    }
 }
 
diff --git a/src/panfrost/vulkan/panvk_vX_pipeline.c b/src/panfrost/vulkan/panvk_vX_pipeline.c
index e7d1dde5fd0..f1bcbc50e80 100644
--- a/src/panfrost/vulkan/panvk_vX_pipeline.c
+++ b/src/panfrost/vulkan/panvk_vX_pipeline.c
@@ -827,6 +827,9 @@ panvk_pipeline_builder_collect_varyings(struct panvk_pipeline_builder *builder,
    /* TODO: Xfb */
    gl_varying_slot loc;
    BITSET_FOREACH_SET(loc, pipeline->varyings.active, VARYING_SLOT_MAX) {
+      if (pipeline->varyings.varying[loc].format == PIPE_FORMAT_NONE)
+         continue;
+
       enum panvk_varying_buf_id buf_id =
          panvk_varying_buf_id(false, loc);
       unsigned buf_idx = panvk_varying_buf_index(&pipeline->varyings, buf_id);