diff --git a/include/vk_mem_alloc.h b/include/vk_mem_alloc.h
index 9a639c1..81b03b6 100644
--- a/include/vk_mem_alloc.h
+++ b/include/vk_mem_alloc.h
@@ -12732,7 +12732,7 @@ void VmaBlockVector::IncrementallySortBlocks()
 void VmaBlockVector::SortByFreeSize()
 {
     VMA_SORT(m_Blocks.begin(), m_Blocks.end(),
-        [](auto* b1, auto* b2)
+        [](VmaDeviceMemoryBlock* b1, VmaDeviceMemoryBlock* b2) -> bool
         {
             return b1->m_pMetadata->GetSumFreeSize() < b2->m_pMetadata->GetSumFreeSize();
         });