diff --git a/bindings/java/src/net/hyperic/sigar/win32/Pdh.java b/bindings/java/src/net/hyperic/sigar/win32/Pdh.java
index a92584ea..13aae5b0 100644
--- a/bindings/java/src/net/hyperic/sigar/win32/Pdh.java
+++ b/bindings/java/src/net/hyperic/sigar/win32/Pdh.java
@@ -28,7 +28,7 @@ public class Pdh extends Win32Bindings {
         }
     }
 
-    public void close() throws Win32Exception {
+    public synchronized void close() throws Win32Exception {
         if (h_counter != -1l) {
             pdhRemoveCounter(h_counter);
             h_counter = -1l;
diff --git a/bindings/java/src/net/hyperic/sigar/win32/RegistryKey.java b/bindings/java/src/net/hyperic/sigar/win32/RegistryKey.java
index 35fda300..0076edce 100644
--- a/bindings/java/src/net/hyperic/sigar/win32/RegistryKey.java
+++ b/bindings/java/src/net/hyperic/sigar/win32/RegistryKey.java
@@ -41,7 +41,7 @@ public class RegistryKey extends Win32Bindings
         this.m_hkey = hkey;
     }
     
-    public void close()
+    public synchronized void close()
     {
         if (this.m_hkey != 0) {
             RegCloseKey(this.m_hkey);
diff --git a/bindings/java/src/net/hyperic/sigar/win32/Service.java b/bindings/java/src/net/hyperic/sigar/win32/Service.java
index e4b0fcd0..2a3e1229 100644
--- a/bindings/java/src/net/hyperic/sigar/win32/Service.java
+++ b/bindings/java/src/net/hyperic/sigar/win32/Service.java
@@ -125,7 +125,7 @@ public class Service extends Win32Bindings implements java.io.Serializable
         this.close();
     }
 
-    public void close()
+    public synchronized void close()
     {
         if(this.m_hService != 0) {
             CloseServiceHandle(this.m_hService);