diff --git a/src/compile.cpp b/src/compile.cpp
index 8e7f2ef1ee..2176f17d57 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -235,7 +235,8 @@ class MyThread: public Thread {
          : makeArchitecture(m->system, useNativeFeatures)),
     transition(0),
     traceContext(0),
-    stackLimit(0)
+    stackLimit(0),
+    methodLockIsClean(true)
   {
     arch->acquire();
   }
@@ -256,6 +257,7 @@ class MyThread: public Thread {
   Context* transition;
   TraceContext* traceContext;
   uintptr_t stackLimit;
+  bool methodLockIsClean;
 };
 
 void
@@ -1982,16 +1984,23 @@ void
 releaseLock(MyThread* t, object method, void* stack)
 {
   if (methodFlags(t, method) & ACC_SYNCHRONIZED) {
-    object lock;
-    if (methodFlags(t, method) & ACC_STATIC) {
-      lock = methodClass(t, method);
-    } else {
-      lock = *localObject
-        (t, stackForFrame(t, stack, method), method,
-         savedTargetIndex(t, method));
-    }
+    if (t->methodLockIsClean) {
+      object lock;
+      if (methodFlags(t, method) & ACC_STATIC) {
+        lock = methodClass(t, method);
+      } else {
+        lock = *localObject
+          (t, stackForFrame(t, stack, method), method,
+           savedTargetIndex(t, method));
+      }
     
-    release(t, lock);
+      release(t, lock);
+    } else {
+      // got an exception while trying to acquire the lock for a
+      // synchronized method -- don't try to release it, since we
+      // never succeeded in acquiring it.
+      t->methodLockIsClean = true;
+    }
   }
 }
 
@@ -2764,6 +2773,18 @@ acquireMonitorForObject(MyThread* t, object o)
   }
 }
 
+void
+acquireMonitorForObjectOnEntrance(MyThread* t, object o)
+{
+  if (LIKELY(o)) {
+    t->methodLockIsClean = false;
+    acquire(t, o);
+    t->methodLockIsClean = true;
+  } else {
+    throwNew(t, Machine::NullPointerExceptionType);
+  }
+}
+
 void
 releaseMonitorForObject(MyThread* t, object o)
 {
@@ -3456,7 +3477,7 @@ handleEntrance(MyThread* t, Frame* frame)
   }
 
   handleMonitorEvent
-    (t, frame, getThunk(t, acquireMonitorForObjectThunk));
+    (t, frame, getThunk(t, acquireMonitorForObjectOnEntranceThunk));
 }
 
 void
diff --git a/src/interpret.cpp b/src/interpret.cpp
index 482859e21f..13f3b9e853 100644
--- a/src/interpret.cpp
+++ b/src/interpret.cpp
@@ -322,15 +322,29 @@ setLocalLong(Thread* t, unsigned index, uint64_t value)
 void
 pushFrame(Thread* t, object method)
 {
-  if (t->frame >= 0) {
-    pokeInt(t, t->frame + FrameIpOffset, t->ip);
-  }
-  t->ip = 0;
+  PROTECT(t, method);
 
   unsigned parameterFootprint = methodParameterFootprint(t, method);
   unsigned base = t->sp - parameterFootprint;
   unsigned locals = parameterFootprint;
 
+  if (methodFlags(t, method) & ACC_SYNCHRONIZED) {
+    // Try to acquire the monitor before doing anything else.
+    // Otherwise, if we were to push the frame first, we risk trying
+    // to release a monitor we never successfully acquired when we try
+    // to pop the frame back off.
+    if (methodFlags(t, method) & ACC_STATIC) {
+      acquire(t, methodClass(t, method));
+    } else {
+      acquire(t, peekObject(t, base));
+    }   
+  }
+
+  if (t->frame >= 0) {
+    pokeInt(t, t->frame + FrameIpOffset, t->ip);
+  }
+  t->ip = 0;
+
   if ((methodFlags(t, method) & ACC_NATIVE) == 0) {
     t->code = methodCode(t, method);
 
@@ -349,14 +363,6 @@ pushFrame(Thread* t, object method)
   pokeInt(t, frame + FrameBaseOffset, base);
   pokeObject(t, frame + FrameMethodOffset, method);
   pokeInt(t, t->frame + FrameIpOffset, 0);
-
-  if (methodFlags(t, method) & ACC_SYNCHRONIZED) {
-    if (methodFlags(t, method) & ACC_STATIC) {
-      acquire(t, methodClass(t, method));
-    } else {
-      acquire(t, peekObject(t, base));
-    }   
-  }
 }
 
 void
diff --git a/src/thunks.cpp b/src/thunks.cpp
index dce0885c96..9279cbb811 100644
--- a/src/thunks.cpp
+++ b/src/thunks.cpp
@@ -45,6 +45,7 @@ THUNK(makeBlankArray)
 THUNK(lookUpAddress)
 THUNK(setMaybeNull)
 THUNK(acquireMonitorForObject)
+THUNK(acquireMonitorForObjectOnEntrance)
 THUNK(releaseMonitorForObject)
 THUNK(makeMultidimensionalArray)
 THUNK(makeMultidimensionalArrayFromReference)