diff --git a/src/compiler/build_tables/close_item_set.cpp b/src/compiler/build_tables/item_set_closure.cpp
similarity index 67%
rename from src/compiler/build_tables/close_item_set.cpp
rename to src/compiler/build_tables/item_set_closure.cpp
index 70fd31fe..c05ed6b9 100644
--- a/src/compiler/build_tables/close_item_set.cpp
+++ b/src/compiler/build_tables/item_set_closure.cpp
@@ -1,4 +1,4 @@
-#include "close_item_set.h"
+#include "item_set_closure.h"
 #include "./next_symbols.h"
 #include "grammar.h"
 #include "item.h"
@@ -22,14 +22,11 @@ namespace tree_sitter {
             }
         }
         
-        static vector<Item> closure_in_grammar(const Item &item, const Grammar &grammar) {
-            vector<Item> result;
-            add_item(result, item, grammar);
-            return result;
-        }
-
-        ItemSet close_item_set(const ItemSet &item_set, const Grammar &grammar) {
-            return ItemSet(closure_in_grammar(*item_set.begin(), grammar));
+        ItemSet item_set_closure(const ItemSet &item_set, const Grammar &grammar) {
+            vector<Item> items;
+            for (Item item : item_set)
+                add_item(items, item, grammar);
+            return ItemSet(items);
         }
     }
 }
\ No newline at end of file
diff --git a/src/compiler/build_tables/close_item_set.h b/src/compiler/build_tables/item_set_closure.h
similarity index 70%
rename from src/compiler/build_tables/close_item_set.h
rename to src/compiler/build_tables/item_set_closure.h
index 352d33d1..350e06f4 100644
--- a/src/compiler/build_tables/close_item_set.h
+++ b/src/compiler/build_tables/item_set_closure.h
@@ -7,7 +7,7 @@ namespace tree_sitter {
     class Grammar;
     
     namespace build_tables {
-        ItemSet close_item_set(const ItemSet &item_set, const Grammar &grammar);
+        ItemSet item_set_closure(const ItemSet &item_set, const Grammar &grammar);
     }
 }
 
diff --git a/src/compiler/build_tables/item_set_transitions.cpp b/src/compiler/build_tables/item_set_transitions.cpp
index a0a39131..17a8a6a6 100644
--- a/src/compiler/build_tables/item_set_transitions.cpp
+++ b/src/compiler/build_tables/item_set_transitions.cpp
@@ -1,5 +1,5 @@
 #include "item_set_transitions.h"
-#include "close_item_set.h"
+#include "item_set_closure.h"
 #include "rule_transitions.h"
 
 using std::dynamic_pointer_cast;
@@ -19,7 +19,7 @@ namespace tree_sitter {
             for (Item item : item_set) {
                 for (auto transition : item_transitions(item)) {
                     auto rule = dynamic_pointer_cast<const RuleClass>(transition.first);
-                    auto new_item_set = make_shared<ItemSet>(close_item_set(ItemSet({ *transition.second }), grammar));
+                    auto new_item_set = make_shared<ItemSet>(item_set_closure(ItemSet({ *transition.second }), grammar));
                     if (rule.get()) result.add(rule, new_item_set);
                 }
             }
diff --git a/src/compiler/build_tables/perform.cpp b/src/compiler/build_tables/perform.cpp
index 541b8c8c..00e8f4f1 100644
--- a/src/compiler/build_tables/perform.cpp
+++ b/src/compiler/build_tables/perform.cpp
@@ -1,6 +1,6 @@
 #include "./perform.h"
 #include "item_set.h"
-#include "close_item_set.h"
+#include "item_set_closure.h"
 #include "next_symbols.h"
 #include "item_set_transitions.h"
 #include "rules.h"
@@ -111,7 +111,7 @@ namespace tree_sitter {
 
             pair<ParseTable, LexTable> build() {
                 auto item = Item(ParseTable::START, rules::sym(grammar.start_rule_name), 0);
-                auto item_set = close_item_set(ItemSet({ item }), grammar);
+                auto item_set = item_set_closure(ItemSet({ item }), grammar);
                 add_parse_state(item_set);
                 return pair<ParseTable, LexTable>(parse_table, lex_table);
             }
diff --git a/tree_sitter.xcodeproj/project.pbxproj b/tree_sitter.xcodeproj/project.pbxproj
index f145eafc..4e504d37 100644
--- a/tree_sitter.xcodeproj/project.pbxproj
+++ b/tree_sitter.xcodeproj/project.pbxproj
@@ -32,7 +32,7 @@
 		12EDCFB418820519005A7A07 /* compile.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFAC18820181005A7A07 /* compile.cpp */; };
 		12EDCFBC188205BF005A7A07 /* rule_transitions_spec.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFB6188205BA005A7A07 /* rule_transitions_spec.cpp */; };
 		12EDCFBD188205BF005A7A07 /* perform_spec.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFB7188205BA005A7A07 /* perform_spec.cpp */; };
-		12EDCFC018820880005A7A07 /* close_item_set.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFBE18820880005A7A07 /* close_item_set.cpp */; };
+		12EDCFC018820880005A7A07 /* item_set_closure.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFBE18820880005A7A07 /* item_set_closure.cpp */; };
 		12EDCFC318820A70005A7A07 /* item_set_transitions.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFC118820A70005A7A07 /* item_set_transitions.cpp */; };
 		12EDCFC61882153D005A7A07 /* next_symbols.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12EDCFC41882153D005A7A07 /* next_symbols.cpp */; };
 		12F9A64E182DD5FD00FAF50C /* spec_helper.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 12F9A64C182DD5FD00FAF50C /* spec_helper.cpp */; };
@@ -127,8 +127,8 @@
 		12EDCFAD18820181005A7A07 /* compile.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = compile.h; sourceTree = "<group>"; };
 		12EDCFB6188205BA005A7A07 /* rule_transitions_spec.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = rule_transitions_spec.cpp; sourceTree = "<group>"; };
 		12EDCFB7188205BA005A7A07 /* perform_spec.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = perform_spec.cpp; sourceTree = "<group>"; };
-		12EDCFBE18820880005A7A07 /* close_item_set.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = close_item_set.cpp; sourceTree = "<group>"; };
-		12EDCFBF18820880005A7A07 /* close_item_set.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = close_item_set.h; sourceTree = "<group>"; };
+		12EDCFBE18820880005A7A07 /* item_set_closure.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = item_set_closure.cpp; sourceTree = "<group>"; };
+		12EDCFBF18820880005A7A07 /* item_set_closure.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = item_set_closure.h; sourceTree = "<group>"; };
 		12EDCFC118820A70005A7A07 /* item_set_transitions.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = item_set_transitions.cpp; sourceTree = "<group>"; };
 		12EDCFC218820A70005A7A07 /* item_set_transitions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = item_set_transitions.h; sourceTree = "<group>"; };
 		12EDCFC41882153D005A7A07 /* next_symbols.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = next_symbols.cpp; sourceTree = "<group>"; };
@@ -205,12 +205,12 @@
 		12130618182C84B700FCF928 /* build_tables */ = {
 			isa = PBXGroup;
 			children = (
-				12EDCFBE18820880005A7A07 /* close_item_set.cpp */,
-				12EDCFBF18820880005A7A07 /* close_item_set.h */,
 				12EDCFA218820137005A7A07 /* item.cpp */,
 				12EDCFA318820137005A7A07 /* item.h */,
 				12EDCFA018820137005A7A07 /* item_set.cpp */,
 				12EDCFA118820137005A7A07 /* item_set.h */,
+				12EDCFBE18820880005A7A07 /* item_set_closure.cpp */,
+				12EDCFBF18820880005A7A07 /* item_set_closure.h */,
 				12EDCFC118820A70005A7A07 /* item_set_transitions.cpp */,
 				12EDCFC218820A70005A7A07 /* item_set_transitions.h */,
 				12EDCFC41882153D005A7A07 /* next_symbols.cpp */,
@@ -470,7 +470,7 @@
 				12EDCFB31882039A005A7A07 /* rule_transitions.cpp in Sources */,
 				12FD40D9185FEEDF0041A84E /* pattern_spec.cpp in Sources */,
 				12130617182C3D2900FCF928 /* string.cpp in Sources */,
-				12EDCFC018820880005A7A07 /* close_item_set.cpp in Sources */,
+				12EDCFC018820880005A7A07 /* item_set_closure.cpp in Sources */,
 				12EDCFBD188205BF005A7A07 /* perform_spec.cpp in Sources */,
 				12EDCFC61882153D005A7A07 /* next_symbols.cpp in Sources */,
 				12130611182C3A1100FCF928 /* blank.cpp in Sources */,