diff --git a/src/compiler/build_tables/lex_table_builder.cc b/src/compiler/build_tables/lex_table_builder.cc
index fa8b86f3..1d873ae8 100644
--- a/src/compiler/build_tables/lex_table_builder.cc
+++ b/src/compiler/build_tables/lex_table_builder.cc
@@ -117,6 +117,7 @@ class LexTableBuilderImpl : public LexTableBuilder {
       if (following_tokens != following_tokens_by_token.end()) {
         following_tokens->second.for_each([&](Symbol following_token) {
           following_character_aggregator.apply(grammar.variables[following_token.index].rule);
+          return true;
         });
       }
 
@@ -177,7 +178,9 @@ class LexTableBuilderImpl : public LexTableBuilder {
       keyword_symbols.for_each([&](Symbol keyword_symbol) {
         if (!conflict_manager.possible_homonyms[symbol.index].count(keyword_symbol.index)) {
           matches_all_keywords = false;
+          return false;
         }
+        return true;
       });
       if (!matches_all_keywords) continue;
 
@@ -484,6 +487,7 @@ class LexTableBuilderImpl : public LexTableBuilder {
          }
         }
       }
+      return true;
     });
     return result;
   }
diff --git a/src/compiler/build_tables/lookahead_set.cc b/src/compiler/build_tables/lookahead_set.cc
index 8b16add4..80ec58e1 100644
--- a/src/compiler/build_tables/lookahead_set.cc
+++ b/src/compiler/build_tables/lookahead_set.cc
@@ -35,7 +35,11 @@ bool LookaheadSet::contains(const Symbol &symbol) const {
 bool LookaheadSet::intersects(const LookaheadSet &other) const {
   bool result = false;
   for_each([&](Symbol symbol) {
-    if (other.contains(symbol)) result = true;
+    if (other.contains(symbol)) {
+      result = true;
+      return false;
+    }
+    return true;
   });
   return result;
 }
diff --git a/src/compiler/build_tables/lookahead_set.h b/src/compiler/build_tables/lookahead_set.h
index 6898b5a2..bb9eeff9 100644
--- a/src/compiler/build_tables/lookahead_set.h
+++ b/src/compiler/build_tables/lookahead_set.h
@@ -32,12 +32,12 @@ class LookaheadSet {
          iter != end;
          ++iter) {
       if (*iter) {
-        callback(rules::Symbol::external(iter - begin));
+        if (!callback(rules::Symbol::external(iter - begin))) return;
       }
     }
 
     if (eof) {
-      callback(rules::END_OF_INPUT());
+      if (!callback(rules::END_OF_INPUT())) return;
     }
 
     for (auto begin = terminal_bits.begin(),
@@ -46,7 +46,7 @@ class LookaheadSet {
          iter != end;
          ++iter) {
       if (*iter) {
-        callback(rules::Symbol::terminal(iter - begin));
+        if (!callback(rules::Symbol::terminal(iter - begin))) return;
       }
     }
   }
diff --git a/src/compiler/build_tables/parse_item.cc b/src/compiler/build_tables/parse_item.cc
index 7e4d0c64..729cdc28 100644
--- a/src/compiler/build_tables/parse_item.cc
+++ b/src/compiler/build_tables/parse_item.cc
@@ -187,6 +187,7 @@ size_t hash<ParseItemSet>::operator()(const ParseItemSet &item_set) const {
     hash_combine(&result, lookahead_set.size());
     lookahead_set.for_each([&result](Symbol symbol) {
       hash_combine(&result, symbol);
+      return true;
     });
   }
   return result;
diff --git a/src/compiler/build_tables/parse_table_builder.cc b/src/compiler/build_tables/parse_table_builder.cc
index cd2f2aff..f6a3ce60 100644
--- a/src/compiler/build_tables/parse_table_builder.cc
+++ b/src/compiler/build_tables/parse_table_builder.cc
@@ -239,6 +239,8 @@ class ParseTableBuilderImpl : public ParseTableBuilder {
               }
             }
           }
+
+          return true;
         });
 
       // If the item is unfinished, create a new item by advancing one symbol.
@@ -835,13 +837,15 @@ class ParseTableBuilderImpl : public ParseTableBuilder {
 
       if (!left_tokens.empty() && !right_tokens.empty()) {
         left_tokens.for_each([&](Symbol left_symbol) {
-          if (!left_symbol.is_non_terminal() && !left_symbol.is_built_in()) {
+          if (left_symbol.is_terminal() && !left_symbol.is_built_in()) {
             right_tokens.for_each([&](Symbol right_symbol) {
               if (right_symbol.is_terminal() && !right_symbol.is_built_in()) {
                 following_tokens_by_token[left_symbol].insert(right_symbol);
               }
+              return true;
             });
           }
+          return true;
         });
       }
     }
diff --git a/test/helpers/stream_methods.cc b/test/helpers/stream_methods.cc
index 5e20eb34..1ff791b6 100644
--- a/test/helpers/stream_methods.cc
+++ b/test/helpers/stream_methods.cc
@@ -210,6 +210,7 @@ ostream &operator<<(ostream &stream, const LookaheadSet &lookaheads) {
   stream << "(LookaheadSet";
   lookaheads.for_each([&stream](Symbol symbol) {
     stream << " " << symbol;
+    return true;
   });
   return stream << ")";
 }