diff --git a/java/CMakeLists.txt b/java/CMakeLists.txt
index 382fd3cdb..484517f8b 100644
--- a/java/CMakeLists.txt
+++ b/java/CMakeLists.txt
@@ -59,6 +59,7 @@ set(src_files
 
 set(include_dirs
     ${CMAKE_CURRENT_SOURCE_DIR}/../include/
+    ${CMAKE_CURRENT_SOURCE_DIR}/../node/
     ${Java_INCLUDE_DIRS})
 
 if(WIN32)
diff --git a/java/jni/Android.mk b/java/jni/Android.mk
index 15ba38753..56e6fb80e 100644
--- a/java/jni/Android.mk
+++ b/java/jni/Android.mk
@@ -4,6 +4,7 @@ include $(CLEAR_VARS)
 
 LOCAL_MODULE := ZeroTierOneJNI
 LOCAL_C_INCLUDES := $(ZT1)/include
+LOCAL_C_INCLUDES += $(ZT1)/node
 LOCAL_LDLIBS := -llog
 # LOCAL_CFLAGS := -g
 
diff --git a/java/jni/Application.mk b/java/jni/Application.mk
index 8b6c80208..0f3697300 100644
--- a/java/jni/Application.mk
+++ b/java/jni/Application.mk
@@ -1,5 +1,5 @@
-APP_ABI := armeabi armeabi-v7a arm64-v8a x86
-APP_STL := gnustl_static
-APP_CPPFLAGS += -Wall -fPIE -fstack-protector -fexceptions
+NDK_TOOLCHAIN_VERSION := clang
+APP_STL := c++_static
+APP_CPPFLAGS := -O2 -fPIE -fvectorize -Wall -fstack-protector -fexceptions -fno-strict-aliasing
 APP_PLATFORM := android-14
 APP_ABI := all
diff --git a/java/jni/com_zerotierone_sdk_Node.cpp b/java/jni/com_zerotierone_sdk_Node.cpp
index e8f7272bd..e98342e7a 100644
--- a/java/jni/com_zerotierone_sdk_Node.cpp
+++ b/java/jni/com_zerotierone_sdk_Node.cpp
@@ -30,6 +30,7 @@
 #include "ZT1_jnilookup.h"
 
 #include <ZeroTierOne.h>
+#include "Mutex.hpp"
 
 #include <map>
 #include <string>
@@ -192,9 +193,9 @@ namespace {
     {
         LOGV("EventCallback");
         JniRef *ref = (JniRef*)userData;
-        if(ref->node != node)
+        if(ref->node != node && event != ZT1_EVENT_UP)
         {
-            LOGE("Nodes not equal. ref->node %p, node %p", ref->node, node);
+            LOGE("Nodes not equal. ref->node %p, node %p. Event: %d", ref->node, node, event);
             return;
         }
         JNIEnv *env = NULL;
@@ -478,9 +479,11 @@ namespace {
 
     typedef std::map<uint64_t, JniRef*> NodeMap;
     static NodeMap nodeMap;
+    ZeroTier::Mutex nodeMapMutex;
 
     ZT1_Node* findNode(uint64_t nodeId)
     {
+        ZeroTier::Mutex::Lock lock(nodeMapMutex);
         NodeMap::iterator found = nodeMap.find(nodeId);
         if(found != nodeMap.end())
         {
@@ -633,8 +636,10 @@ JNIEXPORT jobject JNICALL Java_com_zerotier_sdk_Node_node_1init(
         return resultObject;
     }
 
+    ZeroTier::Mutex::Lock lock(nodeMapMutex);
     ref->node = node;
     nodeMap.insert(std::make_pair(ref->id, ref));
+    
 
     return resultObject;
 }
@@ -650,7 +655,12 @@ JNIEXPORT void JNICALL Java_com_zerotier_sdk_Node_node_1delete(
     LOGV("Destroying ZT1_Node struct");
     uint64_t nodeId = (uint64_t)id;
 
-    NodeMap::iterator found = nodeMap.find(nodeId);
+    NodeMap::iterator found;
+    {
+        ZeroTier::Mutex::Lock lock(nodeMapMutex);  
+        found = nodeMap.find(nodeId);
+    }
+
     if(found != nodeMap.end())
     {
         JniRef *ref = found->second;
@@ -819,6 +829,7 @@ JNIEXPORT jobject JNICALL Java_com_zerotier_sdk_Node_processWirePacket(
     jbyteArray addressArray = (jbyteArray)env->CallObjectMethod(addrObject, getAddressMethod);
     if(addressArray == NULL)
     {
+        LOGE("Unable to call getAddress()");
         // unable to call getAddress()
         return createResultObject(env, ZT1_RESULT_FATAL_ERROR_INTERNAL);
     }
@@ -849,6 +860,7 @@ JNIEXPORT jobject JNICALL Java_com_zerotier_sdk_Node_processWirePacket(
     }
     else
     {
+        LOGE("Unknown IP version");
         // unknown address type
         env->ReleasePrimitiveArrayCritical(addressArray, addr, 0);
         return createResultObject(env, ZT1_RESULT_FATAL_ERROR_INTERNAL);
@@ -856,6 +868,11 @@ JNIEXPORT jobject JNICALL Java_com_zerotier_sdk_Node_processWirePacket(
     env->ReleasePrimitiveArrayCritical(addressArray, addr, 0);
 
     unsigned int packetLength = env->GetArrayLength(in_packetData);
+    if(packetLength == 0)
+    {
+        LOGE("Empty packet?!?");
+        return createResultObject(env, ZT1_RESULT_FATAL_ERROR_INTERNAL);
+    }
     void *packetData = env->GetPrimitiveArrayCritical(in_packetData, NULL);
     void *localData = malloc(packetLength);
     memcpy(localData, packetData, packetLength);