diff --git a/engines/agos/agos.h b/engines/agos/agos.h
index 263811b..1d6f385 100644
--- a/engines/agos/agos.h
+++ b/engines/agos/agos.h
@@ -1285,6 +1285,8 @@ class AGOSEngine_PN : public AGOSEngine {
 	void introSeq();
 	void setupBoxes();
 	int readfromline();
+	
+	void printStackChain();
 public:
 	AGOSEngine_PN(OSystem *system);
 	~AGOSEngine_PN();
@@ -1359,6 +1361,10 @@ public:
 	void opn_opcode63();
 
 	StackFrame *_stackbase;
+	struct {
+		int val;
+		void *tag;
+	} _longJmpEmulation;
 
 	byte *_dataBase, *_textBase;
 	uint32 _dataBaseSize, _textBaseSize;
diff --git a/engines/agos/pn.cpp b/engines/agos/pn.cpp
index d92efa9..e5bac77 100644
--- a/engines/agos/pn.cpp
+++ b/engines/agos/pn.cpp
@@ -34,6 +34,10 @@ namespace AGOS {
 
 AGOSEngine_PN::AGOSEngine_PN(OSystem *system)
 	: AGOSEngine(system) {
+	
+	_stackbase = 0;
+	_longJmpEmulation.val = 0;
+	_longJmpEmulation.tag = 0;
 
 	_dataBase = 0;
 	_dataBaseSize = 0;
@@ -70,7 +74,7 @@ AGOSEngine_PN::AGOSEngine_PN(OSystem *system)
 	_objects = 0;
 	_objectCountS = 0;
 
-        _bp = 0;
+	_bp = 0;
 	_xofs = 0;
 	_havinit = 0;
 	_seed = 0;
diff --git a/engines/agos/script_pn.cpp b/engines/agos/script_pn.cpp
index 4f9aab2..c20e425 100644
--- a/engines/agos/script_pn.cpp
+++ b/engines/agos/script_pn.cpp
@@ -30,10 +30,23 @@
 
 namespace AGOS {
 
+#define LONGJMP_EMU
+
 enum {
 	kJmpClassNum = -1
 };
 
+void AGOSEngine_PN::printStackChain() {
+	StackFrame *stackbase = _stackbase;
+	if (!stackbase) return;
+	printf("     ");
+	while (stackbase) {
+		printf(" > %p", (const void *)stackbase);
+		stackbase = stackbase->nextframe;
+	}
+	printf("\n");
+}
+
 #define OPCODE(x)	_OPCODE(AGOSEngine_PN, x)
 
 void AGOSEngine_PN::setupOpcodes() {
@@ -324,8 +337,16 @@ void AGOSEngine_PN::opn_opcode24() {
 	// That value then is returned to actCallD, which once again
 	// returns it. In the end, this amounts to a setScriptReturn(true)
 	// (but possibly in a different level than the current one).
+printf("opn_opcode24: classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff, _stackbase && _cjmpbuff == _stackbase->savearea);
+printStackChain();
+#ifdef LONGJMP_EMU
+	_longJmpEmulation.val = 2;
+	_longJmpEmulation.tag = _stackbase->savearea;
+#else
 	longjmp(*(_stackbase->savearea), 2);
 	setScriptReturn(false);
+#endif
 }
 
 void AGOSEngine_PN::opn_opcode25() {
@@ -334,8 +355,16 @@ void AGOSEngine_PN::opn_opcode25() {
 	// That value then is returned to actCallD, which once again
 	// returns it. In the end, this amounts to a setScriptReturn(false)
 	// (but possibly in a different level than the current one).
+printf("opn_opcode25: classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff, _stackbase && _cjmpbuff == _stackbase->savearea);
+printStackChain();
+#ifdef LONGJMP_EMU
+	_longJmpEmulation.val = 1;
+	_longJmpEmulation.tag = _stackbase->savearea;
+#else
 	longjmp(*(_stackbase->savearea), 1);
 	setScriptReturn(false);
+#endif
 }
 
 void AGOSEngine_PN::opn_opcode26() {
@@ -354,15 +383,26 @@ void AGOSEngine_PN::opn_opcode27() {
 void AGOSEngine_PN::opn_opcode28() {
 	addstack(varval());
 	_stackbase->savearea = _cjmpbuff;
+printf("opn_opcode28: classnum %d, _cjmpbuff %p\n",
+		_stackbase ? _stackbase->classnum : -1000, (const void *)_cjmpbuff);
+printStackChain();
 	setScriptReturn(false);
 }
 
 void AGOSEngine_PN::opn_opcode29() {
 	popstack(varval());
-	// Jump back to the last doline indicated by the top stackfram.
+	// Jump back to the last doline indicated by the top stackframe.
 	// The -1 tells it to simply go on with its business.
+printf("opn_opcode29: classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff, _stackbase && _cjmpbuff == _stackbase->savearea);
+printStackChain();
+#ifdef LONGJMP_EMU
+	_longJmpEmulation.val = -1;
+	_longJmpEmulation.tag = _stackbase->savearea;
+#else
 	longjmp(*(_stackbase->savearea), -1);
 	setScriptReturn(false);
+#endif
 }
 
 void AGOSEngine_PN::opn_opcode30() {
@@ -520,19 +560,38 @@ void AGOSEngine_PN::opn_opcode39() {
 }
 
 void AGOSEngine_PN::opn_opcode40() {
-	setScriptReturn(doaction() | doaction());
+	int a = doaction();
+#ifdef LONGJMP_EMU
+	if (_longJmpEmulation.val != 0)
+		return;
+#endif
+	int b = doaction();
+	setScriptReturn(a | b);
 }
 
 void AGOSEngine_PN::opn_opcode41() {
-	setScriptReturn(doaction() & doaction());
+	int a = doaction();
+#ifdef LONGJMP_EMU
+	if (_longJmpEmulation.val != 0)
+		return;
+#endif
+	int b = doaction();
+	setScriptReturn(a & b);
 }
 
 void AGOSEngine_PN::opn_opcode42() {
-	setScriptReturn(doaction() ^ doaction());
+	int a = doaction();
+#ifdef LONGJMP_EMU
+	if (_longJmpEmulation.val != 0)
+		return;
+#endif
+	int b = doaction();
+	setScriptReturn(a ^ b);
 }
 
 void AGOSEngine_PN::opn_opcode43() {
-	setScriptReturn(!(doaction()));
+	int a = doaction();
+	setScriptReturn(!a);
 }
 
 void AGOSEngine_PN::opn_opcode44() {
@@ -877,18 +936,50 @@ int AGOSEngine_PN::doline(int needsave) {
 	int x;
 	jmp_buf *old_jmpbuf = NULL;
 	jmp_buf *mybuf;
+	
+	assert(!_stackbase == !needsave);
 
-	mybuf = (jmp_buf *)malloc(sizeof(jmp_buf));
+	mybuf = (jmp_buf *)calloc(1, sizeof(jmp_buf));
 	if (mybuf == NULL)
 		error("doline: Out of memory - stack overflow");
 
+#ifdef LONGJMP_EMU
+	_longJmpEmulation.val = 0;
+	_longJmpEmulation.tag = mybuf;
+
+setjmp_emu_label:
+	if (_longJmpEmulation.tag != mybuf)
+		return 0;
+
+	x = _longJmpEmulation.val;
+	_longJmpEmulation.val = 0;
+#else
 	x = setjmp(*mybuf);
+#endif
 	// Looking at the longjmp calls below, x can be -1, 1 or 2
 	// (and of course 0 when it returns directly, as always).
+	
+	if (x == 0) {
+		// Remember the previous active jmpbuf (gets restored 
+		// when a longjmp with a positive param occurs).
+		old_jmpbuf = _cjmpbuff;
+		_cjmpbuff = mybuf;
+		if (needsave)
+			_stackbase->savearea = mybuf;
+	}
+
+printf("doline(%d): setjmp returned %d -- classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		needsave, x,
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff,
+			(x==0) || _stackbase && _cjmpbuff == _stackbase->savearea);
+printStackChain();
+
 	if (x > 0) {
 		dumpstack();
 		// Restore the active jmpbuf to its previous value,
 		// then return the longjmp value (will be 2-1=1 or 1-1=0).
+printf("    restoring _cjmpbuff to old_jmpbuf %p, savearea %p (%d)\n",
+		(const void *)old_jmpbuf, _stackbase ? (const void *)_stackbase->savearea : 0, _stackbase && _stackbase->savearea == old_jmpbuf);
 		_cjmpbuff = old_jmpbuf;
 		free((char *)mybuf);
 		return (x - 1);
@@ -899,16 +990,11 @@ int AGOSEngine_PN::doline(int needsave) {
 		// This is used to "return" over possibly multiple
 		// layers of nested script invocations.
 		// Kind of like throwing an exception.
+printf("    restoring _cjmpbuff to mybuf %p, savearea %p (%d)\n",
+		(const void *)mybuf, _stackbase ? (const void *)_stackbase->savearea : 0, _stackbase && _stackbase->savearea == mybuf);
 		_cjmpbuff = mybuf;
 		goto carryon;
 	}
-	
-	// Remember the previous active jmpbuf (gets restored 
-	// above when a longjmp with a positive param occurs).
-	old_jmpbuf = _cjmpbuff;
-	_cjmpbuff = mybuf;
-	if (needsave)
-		_stackbase->savearea = mybuf;
 
 	do {
 		_linct = ((*_linebase) & 127) - 1;
@@ -922,6 +1008,10 @@ int AGOSEngine_PN::doline(int needsave) {
 carryon:
 		do {
 			x = doaction();
+#ifdef LONGJMP_EMU
+			if (_longJmpEmulation.val != 0)
+				goto setjmp_emu_label;
+#endif
 		} while (x && !shouldQuit());
 
 skipln:
@@ -1063,7 +1153,7 @@ void AGOSEngine_PN::addstack(int type) {
 	StackFrame *a;
 	int i;
 
-	a = (StackFrame *)malloc(sizeof(StackFrame));
+	a = (StackFrame *)calloc(1, sizeof(StackFrame));
 	if (a == NULL)
 		error("addstack: Out of memory - stack overflow");
 
@@ -1100,6 +1190,8 @@ void AGOSEngine_PN::junkstack() {
 		error("junkstack: Stack underflow or unknown longjmp");
 
 	a = _stackbase->nextframe;
+printf("junkstack: classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff, _stackbase && _cjmpbuff == _stackbase->savearea);
 	if (_stackbase->classnum == kJmpClassNum)
 		free((char *)_stackbase->savearea);
 	free((char *)_stackbase);
@@ -1107,10 +1199,16 @@ void AGOSEngine_PN::junkstack() {
 }
 
 void AGOSEngine_PN::popstack(int type) {
-	int i;
+	int i = 0;
 
-	while ((_stackbase != NULL) && (_stackbase->classnum != type))
+	while ((_stackbase != NULL) && (_stackbase->classnum != type)) {
 		junkstack();
+		++i;
+	}
+
+printf("popstack(%d): dropped %d, now: classnum %d, savearea %p, _cjmpbuff %p (%d)\n",
+		type, i, 
+		_stackbase ? _stackbase->classnum : -1000, _stackbase ? (const void *)_stackbase->savearea : 0, (const void *)_cjmpbuff, _stackbase && _cjmpbuff == _stackbase->savearea);
 
 	if (_stackbase == NULL)
 		error("popstack: Stack underflow or unknown longjmp");