diff --git a/source/glest_game/gui/gui.cpp b/source/glest_game/gui/gui.cpp
index 59fc1387..ad1467d7 100644
--- a/source/glest_game/gui/gui.cpp
+++ b/source/glest_game/gui/gui.cpp
@@ -349,7 +349,18 @@ void Gui::mouseDoubleClickLeftGraphics(int x, int y){
 void Gui::groupKey(int groupIndex) {
 	if(isKeyDown(vkControl)){
 		if(SystemFlags::getSystemSettingType(SystemFlags::debugSystem).enabled) SystemFlags::OutputDebug(SystemFlags::debugSystem,"In [%s::%s Line: %d] groupIndex = %d\n",__FILE__,__FUNCTION__,__LINE__,groupIndex);
-		selection.assignGroup(groupIndex,!isKeyDown(vkShift));
+		bool allAssigned=true;
+		bool clearGroup=!isKeyDown(vkShift);
+//		if(!clearGroup){
+//			Unit* unit=selection.getFrontUnit();
+//			if(unit!=null && unit->getType()->getMultiSelect()==false){
+//				return;
+//			}
+//		}
+		allAssigned=selection.assignGroup(groupIndex,clearGroup);
+		if(!allAssigned){
+			console->addStdMessage("GroupAssignFailed");
+		}
 	}
 	else{
 		if(SystemFlags::getSystemSettingType(SystemFlags::debugSystem).enabled) SystemFlags::OutputDebug(SystemFlags::debugSystem,"In [%s::%s Line: %d] groupIndex = %d\n",__FILE__,__FUNCTION__,__LINE__,groupIndex);
diff --git a/source/glest_game/gui/selection.cpp b/source/glest_game/gui/selection.cpp
index 69911923..721f8528 100644
--- a/source/glest_game/gui/selection.cpp
+++ b/source/glest_game/gui/selection.cpp
@@ -211,7 +211,7 @@ bool Selection::hasUnit(const Unit* unit) const {
 	return find(selectedUnits.begin(), selectedUnits.end(), unit) != selectedUnits.end();
 }
 
-void Selection::assignGroup(int groupIndex, bool clearGroup,const UnitContainer *pUnits) {
+bool Selection::assignGroup(int groupIndex, bool clearGroup,const UnitContainer *pUnits) {
 	if(groupIndex < 0 || groupIndex >= maxGroups) {
 		throw megaglest_runtime_error("Invalid value for groupIndex = " + intToStr(groupIndex));
 	}
@@ -227,17 +227,40 @@ void Selection::assignGroup(int groupIndex, bool clearGroup,const UnitContainer
 		addUnits = pUnits;
 	}
 	for(unsigned int i = 0; i < addUnits->size(); ++i) {
-		groups[groupIndex].push_back((*addUnits)[i]);
+		if(false == addUnitToGroup(groupIndex,(*addUnits)[i])){
+			// don't try to add more, group is full
+			return false;
+		}
 	}
+	return true;
 }
 
-void Selection::addUnitToGroup(int groupIndex,Unit *unit) {
+/**
+ * returns false if group is already full
+ */
+bool Selection::addUnitToGroup(int groupIndex,Unit *unit) {
 	if(groupIndex < 0 || groupIndex >= maxGroups) {
 		throw megaglest_runtime_error("Invalid value for groupIndex = " + intToStr(groupIndex));
 	}
+	bool alreadyExists=false;
+	bool groupIsFull=(int)groups[groupIndex].size() >= Config::getInstance().getInt("MaxUnitSelectCount",intToStr(maxUnits).c_str());
 
-	if(unit != NULL) {
+	for(int i = 0; i < (int)groups[groupIndex].size(); ++i) {
+		if(groups[groupIndex][i] == unit) {
+			alreadyExists=true;
+			break;
+		}
+	}
+
+	if(alreadyExists){
+		return true;
+	}
+	else if(unit != NULL && !groupIsFull) {
 		groups[groupIndex].push_back(unit);
+		return true;
+	}
+	else{
+		return false;
 	}
 }
 
diff --git a/source/glest_game/gui/selection.h b/source/glest_game/gui/selection.h
index 0c58cac9..5c2e6c65 100644
--- a/source/glest_game/gui/selection.h
+++ b/source/glest_game/gui/selection.h
@@ -89,8 +89,8 @@ public:
 	Vec3f getRefPos() const;
 	bool hasUnit(const Unit* unit) const;
 	
-	void assignGroup(int groupIndex, bool clearGroup=true, const UnitContainer *pUnits=NULL);
-	void addUnitToGroup(int groupIndex,Unit *unit);
+	bool assignGroup(int groupIndex, bool clearGroup=true, const UnitContainer *pUnits=NULL);
+	bool addUnitToGroup(int groupIndex,Unit *unit);
 	void removeUnitFromGroup(int groupIndex,int UnitId);
 	void recallGroup(int groupIndex, bool clearSelection=true);