diff --git a/src/add-ons/kernel/file_systems/userlandfs/server/haiku_block_cache.cpp b/src/add-ons/kernel/file_systems/userlandfs/server/haiku_block_cache.cpp
index a6d07c5c92..029044ff3a 100644
--- a/src/add-ons/kernel/file_systems/userlandfs/server/haiku_block_cache.cpp
+++ b/src/add-ons/kernel/file_systems/userlandfs/server/haiku_block_cache.cpp
@@ -1071,7 +1071,7 @@ block_cache_sync_etc(void *_cache, off_t blockNumber, size_t numBlocks)
 	if (blockNumber < 0 || blockNumber >= cache->max_blocks) {
 		panic("block_cache_sync_etc: invalid block number %Ld (max %Ld)",
 			blockNumber, cache->max_blocks - 1);
-		return NULL;
+		return B_ERROR;
 	}
 
 	BenaphoreLocker locker(&cache->lock);
diff --git a/src/system/kernel/cache/block_cache.cpp b/src/system/kernel/cache/block_cache.cpp
index 235d623efa..a1991c340c 100644
--- a/src/system/kernel/cache/block_cache.cpp
+++ b/src/system/kernel/cache/block_cache.cpp
@@ -1182,7 +1182,7 @@ block_cache_sync_etc(void *_cache, off_t blockNumber, size_t numBlocks)
 	if (blockNumber < 0 || blockNumber >= cache->max_blocks) {
 		panic("block_cache_sync_etc: invalid block number %Ld (max %Ld)",
 			blockNumber, cache->max_blocks - 1);
-		return NULL;
+		return B_ERROR;
 	}
 
 	BenaphoreLocker locker(&cache->lock);