diff --git a/lib/mergeset/part.go b/lib/mergeset/part.go
index dc1b92ab8b..4554e10828 100644
--- a/lib/mergeset/part.go
+++ b/lib/mergeset/part.go
@@ -42,7 +42,7 @@ func SetDataBlocksCacheSize(size int) {
 func getMaxInmemoryBlocksCacheSize() int {
 	maxInmemoryBlockCacheSizeOnce.Do(func() {
 		if maxInmemoryBlockCacheSize <= 0 {
-			maxIndexBlockCacheSize = int(0.25 * float64(memory.Allowed()))
+			maxInmemoryBlockCacheSize = int(0.25 * float64(memory.Allowed()))
 		}
 	})
 	return maxInmemoryBlockCacheSize