diff --git a/src/main/java/org/codelibs/fess/timer/SystemMonitorTarget.java b/src/main/java/org/codelibs/fess/timer/SystemMonitorTarget.java
index 67836571b..0445ee3e0 100644
--- a/src/main/java/org/codelibs/fess/timer/SystemMonitorTarget.java
+++ b/src/main/java/org/codelibs/fess/timer/SystemMonitorTarget.java
@@ -90,14 +90,14 @@ public class SystemMonitorTarget implements TimeoutTarget {
         final Mem mem = jvmStats.getMem();
         buf.append("\"memory\":{");
         buf.append("\"heap\":{");
-        append(buf, "used", () -> mem.getHeapUsed().bytesAsInt()).append(',');
-        append(buf, "committed", () -> mem.getHeapCommitted().bytesAsInt()).append(',');
-        append(buf, "max", () -> mem.getHeapMax().bytesAsInt()).append(',');
+        append(buf, "used", () -> mem.getHeapUsed().getBytes()).append(',');
+        append(buf, "committed", () -> mem.getHeapCommitted().getBytes()).append(',');
+        append(buf, "max", () -> mem.getHeapMax().getBytes()).append(',');
         append(buf, "percent", () -> mem.getHeapUsedPercent());
         buf.append("},");
         buf.append("\"non_heap\":{");
-        append(buf, "used", () -> mem.getNonHeapUsed().bytesAsInt()).append(',');
-        append(buf, "committed", () -> mem.getNonHeapCommitted().bytesAsInt());
+        append(buf, "used", () -> mem.getNonHeapUsed().getBytes()).append(',');
+        append(buf, "committed", () -> mem.getNonHeapCommitted().getBytes());
         buf.append('}');
         buf.append("},");
         final List<BufferPool> bufferPools = jvmStats.getBufferPools();
@@ -106,8 +106,8 @@ public class SystemMonitorTarget implements TimeoutTarget {
             final StringBuilder b = new StringBuilder();
             b.append('"').append(StringEscapeUtils.escapeJson(p.getName())).append("\":{");
             append(b, "count", () -> p.getCount()).append(',');
-            append(b, "used", () -> p.getUsed().bytesAsInt()).append(',');
-            append(b, "capacity", () -> p.getTotalCapacity().bytesAsInt()).append('}');
+            append(b, "used", () -> p.getUsed().getBytes()).append(',');
+            append(b, "capacity", () -> p.getTotalCapacity().getBytes()).append('}');
             return b.toString();
         }).collect(Collectors.joining(",")));
         buf.append("},");