diff --git a/common/mapsystem/tile_sheet.cpp b/common/mapsystem/tile_sheet.cpp
index 9608a5e..434c259 100644
--- a/common/mapsystem/tile_sheet.cpp
+++ b/common/mapsystem/tile_sheet.cpp
@@ -33,6 +33,10 @@ SDL_Surface* TileSheet::LoadSurface(std::string fname, Uint16 w, Uint16 h) {
 	xCount = image.GetSurface()->w / w;
 	yCount = image.GetSurface()->h / h;
 	totalCount = xCount * yCount;
+
+	//set begin & end (usually temporary)
+	begin = 0;
+	end = totalCount;
 }
 
 SDL_Surface* TileSheet::GetSurface() {
diff --git a/common/mapsystem/tile_sheet.hpp b/common/mapsystem/tile_sheet.hpp
index 1dfa94b..c872b5f 100644
--- a/common/mapsystem/tile_sheet.hpp
+++ b/common/mapsystem/tile_sheet.hpp
@@ -36,6 +36,7 @@ public:
 
 	//these load/set functions need to be followed by bookkeeping code
 	//w & h are the width & height of individual tiles
+	//TODO: rename these
 	SDL_Surface* LoadSurface(std::string fname, Uint16 w, Uint16 h);
 	SDL_Surface* GetSurface();
 	void FreeSurface();
diff --git a/common/mapsystem/tile_sheet_manager.cpp b/common/mapsystem/tile_sheet_manager.cpp
index 7f0275b..07e3bc8 100644
--- a/common/mapsystem/tile_sheet_manager.cpp
+++ b/common/mapsystem/tile_sheet_manager.cpp
@@ -29,11 +29,16 @@ TileSheet* TileSheetManager::LoadSheet(std::string fname, Uint16 w, Uint16 h) {
 	//get the key
 	std::string key = truncatePath(fname);
 
-	//override what's already here
-	sheetMap.erase(key);
+	//don't override what's already here
+	if (sheetMap.find(key) != sheetMap.end()) {
+		throw(std::runtime_error("Cannot load duplicate tile sheets"));
+	}
 
+	//load & setup the sheet object
 	sheetMap[key].LoadSurface(fname, w, h);
+	sheetMap[key].SetBegin(rangeEnd);
 	rangeEnd += sheetMap[key].GetTotalCount();
+	sheetMap[key].SetEnd(rangeEnd);
 }
 
 void TileSheetManager::DrawTo(SDL_Surface* const dest, int x, int y, int tileIndex) {
diff --git a/common/mapsystem/tile_Sheet_manager.hpp b/common/mapsystem/tile_sheet_manager.hpp
similarity index 95%
rename from common/mapsystem/tile_Sheet_manager.hpp
rename to common/mapsystem/tile_sheet_manager.hpp
index 2fea37c..954da94 100644
--- a/common/mapsystem/tile_Sheet_manager.hpp
+++ b/common/mapsystem/tile_sheet_manager.hpp
@@ -44,6 +44,8 @@ public:
 
 	int SetRangeEnd(int i) { return rangeEnd += i; }
 	int GetRangeEnd() const { return rangeEnd; }
+
+	std::map<std::string, TileSheet>* GetSheetMap() { return &sheetMap; }
 private:
 	std::map<std::string, TileSheet> sheetMap;
 	int rangeEnd = 0;