diff --git a/android/src/org/rockbox/monitors/HeadphoneMonitor.java b/android/src/org/rockbox/monitors/HeadphoneMonitor.java
index 99d2f7ab8a..72a2f262f2 100644
--- a/android/src/org/rockbox/monitors/HeadphoneMonitor.java
+++ b/android/src/org/rockbox/monitors/HeadphoneMonitor.java
@@ -29,7 +29,6 @@ import android.content.IntentFilter;
 public class HeadphoneMonitor extends BroadcastReceiver
 {
     @SuppressWarnings("unused")
-    private int mHpState; /* read by native code */
 
     public HeadphoneMonitor(Context c)
     {
@@ -45,7 +44,7 @@ public class HeadphoneMonitor extends BroadcastReceiver
     public void onReceive(Context arg0, Intent intent)
     {
         int state = intent.getIntExtra("state", -1);
-        mHpState = state;   
+        postHpStateChanged(state);
     }
 
     /* audio becoming noise acts as headphones extracted */
@@ -54,7 +53,9 @@ public class HeadphoneMonitor extends BroadcastReceiver
         @Override
         public void onReceive(Context arg0, Intent arg1)
         {
-            mHpState = 0;   
+            postHpStateChanged(0);   
         }
     }
+    
+    private synchronized native void postHpStateChanged(int state);
 }
diff --git a/firmware/target/hosted/android/button-android.c b/firmware/target/hosted/android/button-android.c
index c913a3d7f7..6751effd1b 100644
--- a/firmware/target/hosted/android/button-android.c
+++ b/firmware/target/hosted/android/button-android.c
@@ -34,8 +34,6 @@ extern JNIEnv *env_ptr;
 extern jclass  RockboxService_class;
 extern jobject RockboxService_instance;
 
-static jobject HeadphoneMonitor_instance;
-static jfieldID headphone_state;
 static int last_y, last_x;
 static int last_btns;
 
@@ -120,13 +118,9 @@ void button_init_device(void)
     jmethodID constructor =     e->GetMethodID(env_ptr, class,
                                                 "<init>",
                                                 "(Landroid/content/Context;)V");
-    HeadphoneMonitor_instance = e->NewObject(env_ptr, class,
-                                            constructor,
-                                            RockboxService_instance);
-    /* cache the battery level field id */
-    headphone_state = (*env_ptr)->GetFieldID(env_ptr,
-                                            class,
-                                            "mHpState", "I");
+    e->NewObject(env_ptr, class,         
+                        constructor,
+                        RockboxService_instance);
 }
 
 int button_read_device(int *data)
@@ -145,13 +139,23 @@ int button_read_device(int *data)
     return btn;
 }
 
-
-/* Tell if anything is in the jack. */
+static int hp_state;
+JNIEXPORT void JNICALL
+Java_org_rockbox_monitors_HeadphoneMonitor_postCallHungUp(JNIEnv *env,
+                                                        jobject this,
+                                                        jint state)
+{
+    (void)env; (void)this;
+    hp_state = state;
+}
+/* Tell if anything is in the jack.
+ * 
+ * since this is called from the tick task, which isn't attached to
+ * the dalvik VM, it's not permitted to make JNI calls (therefore
+ * we need the above callback) */
 bool headphones_inserted(void)
 {
-    int state = (*env_ptr)->GetIntField(env_ptr, HeadphoneMonitor_instance,
-                                                            headphone_state);
     /* 0 is disconnected, 1 and 2 are connected */
-    return (state == 0) ? false : true;
+    return (hp_state == 0) ? false : true;
 }
 
diff --git a/firmware/target/hosted/android/kernel-android.c b/firmware/target/hosted/android/kernel-android.c
index 80ff88fd12..e3522418fe 100644
--- a/firmware/target/hosted/android/kernel-android.c
+++ b/firmware/target/hosted/android/kernel-android.c
@@ -60,7 +60,13 @@ void interrupt(void)
 }
 
 /*
- * setup a hrtimer to send a signal to our process every tick */
+ * setup a hrtimer to send a signal to our process every tick
+ *
+ * WARNING: JNI calls are not permitted from tick tasks, as the
+ * underlying thread is not attached to the Java VM
+ *
+ * Can be possibly be attached if it really needs to be. but let's
+ * keep this leightweight */
 void tick_start(unsigned int interval_in_ms)
 {
     int ret = 0;