diff --git a/buffer/src/main/java/io/netty/buffer/PoolArena.java b/buffer/src/main/java/io/netty/buffer/PoolArena.java
index d6481128a2..88faa1d123 100644
--- a/buffer/src/main/java/io/netty/buffer/PoolArena.java
+++ b/buffer/src/main/java/io/netty/buffer/PoolArena.java
@@ -468,7 +468,7 @@ abstract class PoolArena<T> implements PoolArenaMetric {
     public long numDeallocations() {
         final long deallocs;
         synchronized (this) {
-            deallocs = deallocationsTiny + deallocationsSmall + allocationsNormal;
+            deallocs = deallocationsTiny + deallocationsSmall + deallocationsNormal;
         }
         return deallocs + deallocationsHuge.value();
     }
@@ -500,11 +500,11 @@ abstract class PoolArena<T> implements PoolArenaMetric {
 
     @Override
     public  long numActiveAllocations() {
-        long val;
+        long val = allocationsTiny.value() + allocationsSmall.value() + allocationsHuge.value()
+                - deallocationsHuge.value();
         synchronized (this) {
-            val = allocationsNormal - deallocationsTiny - deallocationsSmall - allocationsNormal;
+            val += allocationsNormal - (deallocationsTiny + deallocationsSmall + deallocationsNormal);
         }
-        val -= deallocationsHuge.value();
         return val >= 0 ? val : 0;
     }