4 files changed, 41 insertions, 11 deletions

diff --git a/engines/sci/engine/kscripts.cpp b/engines/sci/engine/kscripts.cpp
index b66647e390..9464ba92c8 100644
--- a/engines/sci/engine/kscripts.cpp
+++ b/engines/sci/engine/kscripts.cpp
@@ -265,11 +265,11 @@ reg_t kDisposeScript(EngineState *s, int funct_nr, int argc, reg_t *argv) {
 	if (argv[0].segment)
 		return s->r_acc;
 
-	if (s->seg_manager->scriptIsLoaded(script, SCRIPT_ID)) {
-		int id = s->seg_manager->segGet(script);
-
+	int id = s->seg_manager->segGet(script);
+	Script *scr = s->seg_manager->getScriptIfLoaded(id, SEG_ID);
+	if (scr) {
 		if (s->_executionStack[s->execution_stack_pos].addr.pc.segment != id)
-			s->seg_manager->getScript(id, SEG_ID)->setLockers(1);
+			scr->setLockers(1);
 	}
 
 	script_uninstantiate(s, script);
diff --git a/engines/sci/engine/seg_manager.cpp b/engines/sci/engine/seg_manager.cpp
index b4cbc75d55..ad7b2e8fc1 100644
--- a/engines/sci/engine/seg_manager.cpp
+++ b/engines/sci/engine/seg_manager.cpp
@@ -402,6 +402,13 @@ Script *SegManager::getScript(const int id, idFlag flag) {
 	return (Script *)_heap[seg];
 }
 
+Script *SegManager::getScriptIfLoaded(const int id, idFlag flag) {
+	const int seg = (flag == SCRIPT_ID) ? segGet(id) : id;
+	if (seg < 0 || (uint)seg >= _heap.size() || !_heap[seg] || _heap[seg]->getType() != MEM_OBJ_SCRIPT)
+		return 0;
+	return (Script *)_heap[seg];
+}
+
 // validate the seg
 // return:
 //	false - invalid seg
diff --git a/engines/sci/engine/seg_manager.h b/engines/sci/engine/seg_manager.h
index 9521d84b7b..549363b9aa 100644
--- a/engines/sci/engine/seg_manager.h
+++ b/engines/sci/engine/seg_manager.h
@@ -75,11 +75,13 @@ public:
 	// Returns   : (int) 1 on success, 0 on failure
 	int deallocateScript(int script_nr);
 
-	// Determines whether a script has been loaded yet
-	// Parameters: (int) id: number of the script or ID of the script segment to check for
-	//             (idFlag) flag: Whether to address the script by script number (SCRIPT_ID) or
-	//				by its segment (SEG_ID). SEG_ID is faster than SCRIPT_ID,
-	//				but less convenient.
+	/**
+	 * Determines whether a script has been loaded yet.
+	 * @param id	number of the script or ID of the script segment to check for
+	 * @param flag	whether to address the script by script number (SCRIPT_ID) or
+	 *				by its segment (SEG_ID). SEG_ID is faster than SCRIPT_ID,
+	 *				but less convenient.
+	 */
 	int scriptIsLoaded(int id, idFlag flag);
 
 	// Validate whether the specified public function is exported by the script in the specified segment
@@ -94,8 +96,29 @@ public:
 	// Returns   : (int) The associated segment ID, or -1 if no matching segment exists
 	int segGet(int script_nr) const;
 
+	/**
+	 * Return a pointer to the specified script. If the id is invalid, does not refer
+	 * to a script or the script is not loaded, this will invoke error().
+	 * @param id	number of the script or ID of the script segment to check for
+	 * @param flag	whether to address the script by script number (SCRIPT_ID) or
+	 *				by its segment (SEG_ID). SEG_ID is faster than SCRIPT_ID,
+	 *				but less convenient.
+	 * @return pointer to the Script object
+	 */
 	Script *getScript(int id, idFlag flag);
 
+	/**
+	 * Return a pointer to the specified script. If the id is invalid, does not refer
+	 * to a script or the script is not loaded, this will return NULL.
+	 * @param id	number of the script or ID of the script segment to check for
+	 * @param flag	whether to address the script by script number (SCRIPT_ID) or
+	 *				by its segment (SEG_ID). SEG_ID is faster than SCRIPT_ID,
+	 *				but less convenient.
+	 * @return pointer to the Script object, or NULL
+	 */
+	Script *getScriptIfLoaded(int id, idFlag flag);
+
+
 
 
 	// 1b. Script Initialisation
diff --git a/engines/sci/engine/vm.cpp b/engines/sci/engine/vm.cpp
index e1d3b254e8..c425d462fc 100644
--- a/engines/sci/engine/vm.cpp
+++ b/engines/sci/engine/vm.cpp
@@ -258,7 +258,7 @@ ExecStack *execute_method(EngineState *s, uint16 script, uint16 pubfunct, StackP
 	seg = s->seg_manager->segGet(script);
 
 	if (!s->seg_manager->scriptIsLoaded(seg, SEG_ID))  // Script not present yet?
-		script_instantiate(s, script);
+		seg = script_instantiate(s, script);
 	else
 		s->seg_manager->getScript(seg, SEG_ID)->unmarkDeleted();
 
@@ -528,7 +528,7 @@ void vm_handle_fatal_error(EngineState *s, int line, const char *file) {
 }
 
 static Script *script_locate_by_segment(EngineState *s, SegmentId seg) {
-	return (Script *)GET_SEGMENT(*s->seg_manager, seg, MEM_OBJ_SCRIPT);
+	return s->seg_manager->getScriptIfLoaded(seg, SEG_ID);
 }
 
 static reg_t pointer_add(EngineState *s, reg_t base, int offset) {