diff --git a/src/blockstore/blockstore_disk.cpp b/src/blockstore/blockstore_disk.cpp
index a1804947..8152264f 100644
--- a/src/blockstore/blockstore_disk.cpp
+++ b/src/blockstore/blockstore_disk.cpp
@@ -173,9 +173,7 @@ void blockstore_disk_t::parse_config(std::map<std::string, std::string> & config
     }
     if (data_block_size / bitmap_granularity < 8)
     {
-        fprintf(stderr, "Warning: block_size (%u) / bitmap_granularity (%u) = %u bits. "
-            "Consider using larger block_size or bitmap_granularity for better performance.\n",
-            data_block_size, bitmap_granularity, data_block_size / bitmap_granularity);
+        throw std::runtime_error("Data block size must be at least bitmap_granularity*8");
     }
     if (!data_csum_type)
     {