diff --git a/include/tree_sitter/parser.h b/include/tree_sitter/parser.h
index 40d7c5fc..ef530434 100644
--- a/include/tree_sitter/parser.h
+++ b/include/tree_sitter/parser.h
@@ -92,7 +92,7 @@ ts_parser constructor_name() { \
 /*
  *  Stack
  */
-typedef int state_id;
+typedef short state_id;
 typedef struct {
     size_t size;
     struct {
@@ -187,10 +187,10 @@ typedef enum {
 typedef struct {
     ts_parse_action_type type;
     union {
-        state_id to_state;
+        int to_state;
         struct {
             ts_symbol symbol;
-            int child_count;
+            unsigned short child_count;
         };
     } data;
 } ts_parse_action;
diff --git a/include/tree_sitter/runtime.h b/include/tree_sitter/runtime.h
index 4d9a8ddc..f2dbb09f 100644
--- a/include/tree_sitter/runtime.h
+++ b/include/tree_sitter/runtime.h
@@ -7,7 +7,7 @@ extern "C" {
 
 #include <stdlib.h>
 
-typedef unsigned int ts_symbol;
+typedef unsigned short ts_symbol;
 #define ts_builtin_sym_error 0
 #define ts_builtin_sym_end 1