--- a/src/compiler/glslang_lex.cpp
+++ b/src/compiler/glslang_lex.cpp
@@ -68,6 +68,7 @@ typedef int16_t flex_int16_t;
 typedef uint16_t flex_uint16_t;
 typedef int32_t flex_int32_t;
 typedef uint32_t flex_uint32_t;
+typedef uint64_t flex_uint64_t;
 #else
 typedef signed char flex_int8_t;
 typedef short int flex_int16_t;
@@ -191,6 +192,11 @@ typedef void* yyscan_t;
 typedef struct yy_buffer_state *YY_BUFFER_STATE;
 #endif

+#ifndef YY_TYPEDEF_YY_SIZE_T
+#define YY_TYPEDEF_YY_SIZE_T
+typedef size_t yy_size_t;
+#endif
+
 #define EOB_ACT_CONTINUE_SCAN 0
 #define EOB_ACT_END_OF_FILE 1
 #define EOB_ACT_LAST_MATCH 2
@@ -204,7 +210,7 @@ typedef struct yy_buffer_state *YY_BUFFER_STATE;
      */
     #define  YY_LESS_LINENO(n) \
             do { \
-                int yyl;\
+                yy_size_t yyl;\
                 for ( yyl = n; yyl < yyleng; ++yyl )\
                     if ( yytext[yyl] == '\n' )\
                         --yylineno;\
@@ -378,7 +379,7 @@ static void yy_fatal_error (yyconst char msg[] ,yyscan_t yyscanner );
  */
 #define YY_DO_BEFORE_ACTION \
 	yyg->yytext_ptr = yy_bp; \
-	yyleng = (size_t) (yy_cp - yy_bp); \
+	yyleng = (yy_size_t) (yy_cp - yy_bp); \
 	yyg->yy_hold_char = *yy_cp; \
 	*yy_cp = '\0'; \
 	yyg->yy_c_buf_p = yy_cp;