diff --git a/src/sdl/Srb2SDL-vc10.vcxproj b/src/sdl/Srb2SDL-vc10.vcxproj
index 105e1def8..d79dde766 100644
--- a/src/sdl/Srb2SDL-vc10.vcxproj
+++ b/src/sdl/Srb2SDL-vc10.vcxproj
@@ -245,6 +245,7 @@
     <ClInclude Include="..\i_sound.h" />
     <ClInclude Include="..\i_system.h" />
     <ClInclude Include="..\i_tcp.h" />
+    <ClInclude Include="..\i_threads.h" />
     <ClInclude Include="..\i_video.h" />
     <ClInclude Include="..\keys.h" />
     <ClInclude Include="..\libdivide.h" />
@@ -304,6 +305,7 @@
     <ClInclude Include="..\st_stuff.h" />
     <ClInclude Include="..\s_sound.h" />
     <ClInclude Include="..\tables.h" />
+    <ClInclude Include="..\taglist.h" />
     <ClInclude Include="..\v_video.h" />
     <ClInclude Include="..\w_wad.h" />
     <ClInclude Include="..\y_inter.h" />
@@ -415,6 +417,7 @@
     <ClCompile Include="..\lua_polyobjlib.c" />
     <ClCompile Include="..\lua_script.c" />
     <ClCompile Include="..\lua_skinlib.c" />
+    <ClCompile Include="..\lua_taglib.c" />
     <ClCompile Include="..\lua_thinkerlib.c" />
     <ClCompile Include="..\lzf.c" />
     <ClCompile Include="..\md5.c" />
@@ -475,10 +478,12 @@
     <ClCompile Include="..\r_things.c" />
     <ClCompile Include="..\screen.c" />
     <ClCompile Include="..\sounds.c" />
+    <ClCompile Include="..\strcasestr.c" />
     <ClCompile Include="..\string.c" />
     <ClCompile Include="..\st_stuff.c" />
     <ClCompile Include="..\s_sound.c" />
     <ClCompile Include="..\tables.c" />
+    <ClCompile Include="..\taglist.c" />
     <ClCompile Include="..\t_facon.c">
       <ExcludedFromBuild>true</ExcludedFromBuild>
     </ClCompile>
diff --git a/src/sdl/Srb2SDL-vc10.vcxproj.filters b/src/sdl/Srb2SDL-vc10.vcxproj.filters
index 404890397..4d2532ca4 100644
--- a/src/sdl/Srb2SDL-vc10.vcxproj.filters
+++ b/src/sdl/Srb2SDL-vc10.vcxproj.filters
@@ -135,6 +135,16 @@
     <ClInclude Include="..\dehacked.h">
       <Filter>D_Doom</Filter>
     </ClInclude>
+    <ClInclude Include="..\deh_lua.h">
+      <Filter>D_Doom</Filter>
+    </ClInclude>
+    <ClInclude Include="..\deh_soc.h">
+      <Filter>D_Doom</Filter>
+    </ClInclude>
+    <ClInclude Include="..\deh_tables.h">
+      <Filter>D_Doom</Filter>
+    </ClInclude>
+
     <ClInclude Include="..\doomdata.h">
       <Filter>D_Doom</Filter>
     </ClInclude>
@@ -288,6 +298,9 @@
     <ClInclude Include="..\i_tcp.h">
       <Filter>I_Interface</Filter>
     </ClInclude>
+    <ClInclude Include="..\i_threads.h">
+      <Filter>I_Interface</Filter>
+    </ClInclude>
     <ClInclude Include="..\i_video.h">
       <Filter>I_Interface</Filter>
     </ClInclude>
@@ -402,6 +415,9 @@
     <ClInclude Include="..\tables.h">
       <Filter>P_Play</Filter>
     </ClInclude>
+    <ClInclude Include="..\taglist.h">
+      <Filter>P_Play</Filter>
+    </ClInclude>
     <ClInclude Include="..\libdivide.h">
       <Filter>R_Rend</Filter>
     </ClInclude>
@@ -600,6 +616,16 @@
     <ClCompile Include="..\dehacked.c">
       <Filter>D_Doom</Filter>
     </ClCompile>
+    <ClCompile Include="..\deh_lua.c">
+      <Filter>D_Doom</Filter>
+    </ClCompile>
+    <ClCompile Include="..\deh_soc.c">
+      <Filter>D_Doom</Filter>
+    </ClCompile>
+    <ClCompile Include="..\deh_tables.c">
+      <Filter>D_Doom</Filter>
+    </ClCompile>
+
     <ClCompile Include="..\d_clisrv.c">
       <Filter>D_Doom</Filter>
     </ClCompile>
@@ -747,6 +773,9 @@
     <ClCompile Include="..\lua_skinlib.c">
       <Filter>LUA</Filter>
     </ClCompile>
+    <ClCompile Include="..\lua_taglib.c">
+      <Filter>LUA</Filter>
+    </ClCompile>
     <ClCompile Include="..\lua_thinkerlib.c">
       <Filter>LUA</Filter>
     </ClCompile>
@@ -792,6 +821,9 @@
     <ClCompile Include="..\string.c">
       <Filter>M_Misc</Filter>
     </ClCompile>
+    <ClCompile Include="..\strcasestr.c">
+      <Filter>M_Misc</Filter>
+    </ClCompile>
     <ClCompile Include="..\comptime.c">
       <Filter>O_Other</Filter>
     </ClCompile>
@@ -852,6 +884,9 @@
     <ClCompile Include="..\tables.c">
       <Filter>P_Play</Filter>
     </ClCompile>
+    <ClCompile Include="..\taglist.c">
+      <Filter>P_Play</Filter>
+    </ClCompile>
     <ClCompile Include="..\t_facon.c">
       <Filter>P_Play</Filter>
     </ClCompile>
diff --git a/src/taglist.c b/src/taglist.c
index ad1b9dc4b..d08750f9b 100644
--- a/src/taglist.c
+++ b/src/taglist.c
@@ -191,6 +191,38 @@ void Taggroup_Add (taggroup_t *garray[], const mtag_t tag, size_t id)
 	group->elements[i] = id;
 }
 
+static void Taggroup_Add_Init(taggroup_t *garray[], const mtag_t tag, size_t id)
+{
+	taggroup_t *group;
+
+	if (tag == MTAG_GLOBAL)
+		return;
+
+	group = garray[(UINT16)tag];
+
+	if (! in_bit_array(tags_available, tag))
+	{
+		num_tags++;
+		set_bit_array(tags_available, tag);
+	}
+
+	// Create group if empty.
+	if (!group)
+		group = garray[(UINT16)tag] = Z_Calloc(sizeof(taggroup_t), PU_LEVEL, NULL);
+	else if (group->elements[group->count - 1] == id)
+		return; // Don't add duplicates
+
+	group->count++;
+
+	if (group->count > group->capacity)
+	{
+		group->capacity = 2 * group->count;
+		group->elements = Z_Realloc(group->elements, group->capacity * sizeof(size_t), PU_LEVEL, NULL);
+	}
+
+	group->elements[group->count - 1] = id;
+}
+
 static size_t total_elements_with_tag (const mtag_t tag)
 {
 	return
@@ -250,17 +282,17 @@ void Taggroup_Remove (taggroup_t *garray[], const mtag_t tag, size_t id)
 
 static void Taglist_AddToSectors (const mtag_t tag, const size_t itemid)
 {
-	Taggroup_Add(tags_sectors, tag, itemid);
+	Taggroup_Add_Init(tags_sectors, tag, itemid);
 }
 
 static void Taglist_AddToLines (const mtag_t tag, const size_t itemid)
 {
-	Taggroup_Add(tags_lines, tag, itemid);
+	Taggroup_Add_Init(tags_lines, tag, itemid);
 }
 
 static void Taglist_AddToMapthings (const mtag_t tag, const size_t itemid)
 {
-	Taggroup_Add(tags_mapthings, tag, itemid);
+	Taggroup_Add_Init(tags_mapthings, tag, itemid);
 }
 
 /// After all taglists have been built for each element (sectors, lines, things),
diff --git a/src/taglist.h b/src/taglist.h
index d045eb827..ae1a81c89 100644
--- a/src/taglist.h
+++ b/src/taglist.h
@@ -41,6 +41,7 @@ typedef struct
 {
 	size_t *elements;
 	size_t count;
+	size_t capacity;
 } taggroup_t;
 
 extern bitarray_t tags_available[];