diff --git a/libavcodec/vulkan_decode.c b/libavcodec/vulkan_decode.c
index cab1028e2c..93aa0ce5b3 100644
--- a/libavcodec/vulkan_decode.c
+++ b/libavcodec/vulkan_decode.c
@@ -257,7 +257,7 @@ int ff_vk_decode_add_slice(AVCodecContext *avctx, FFVulkanDecodePicture *vp,
 
     static const uint8_t startcode_prefix[3] = { 0x0, 0x0, 0x1 };
     const size_t startcode_len = add_startcode ? sizeof(startcode_prefix) : 0;
-    const int nb = *nb_slices;
+    const int nb = nb_slices ? *nb_slices : 0;
     uint8_t *slices;
     uint32_t *slice_off;
     FFVkBuffer *vkbuf;
@@ -266,13 +266,16 @@ int ff_vk_decode_add_slice(AVCodecContext *avctx, FFVulkanDecodePicture *vp,
                       ctx->caps.minBitstreamBufferSizeAlignment;
     new_size = FFALIGN(new_size, ctx->caps.minBitstreamBufferSizeAlignment);
 
-    slice_off = av_fast_realloc(dec->slice_off, &dec->slice_off_max,
-                                (nb + 1)*sizeof(slice_off));
-    if (!slice_off)
-        return AVERROR(ENOMEM);
+    if (offsets) {
+        slice_off = av_fast_realloc(dec->slice_off, &dec->slice_off_max,
+                                    (nb + 1)*sizeof(slice_off));
+        if (!slice_off)
+            return AVERROR(ENOMEM);
 
-    *offsets = dec->slice_off = slice_off;
-    slice_off[nb] = vp->slices_size;
+        *offsets = dec->slice_off = slice_off;
+
+        slice_off[nb] = vp->slices_size;
+    }
 
     vkbuf = vp->slices_buf ? (FFVkBuffer *)vp->slices_buf->data : NULL;
     if (!vkbuf || vkbuf->size < new_size) {
@@ -318,7 +321,9 @@ int ff_vk_decode_add_slice(AVCodecContext *avctx, FFVulkanDecodePicture *vp,
     /* Slice data */
     memcpy(slices + vp->slices_size + startcode_len, data, size);
 
-    *nb_slices = nb + 1;
+    if (nb_slices)
+        *nb_slices = nb + 1;
+
     vp->slices_size += startcode_len + size;
 
     return 0;