diff --git a/frontend/lib/parsing/flex-chpl-lib.cpp b/frontend/lib/parsing/flex-chpl-lib.cpp
index 2cd4f7922519..c8a7fe5217de 100644
--- a/frontend/lib/parsing/flex-chpl-lib.cpp
+++ b/frontend/lib/parsing/flex-chpl-lib.cpp
@@ -281,7 +281,6 @@ 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;
@@ -446,7 +445,7 @@ struct yy_buffer_state
 	/* Number of characters read into yy_ch_buf, not including EOB
 	 * characters.
 	 */
-	yy_size_t yy_n_chars;
+	int yy_n_chars;
 
 	/* Whether we "own" the buffer - i.e., we know we created it,
 	 * and can realloc() it to grow it, and should free() it to
@@ -523,7 +522,7 @@ static void yy_init_buffer ( YY_BUFFER_STATE b, FILE *file , yyscan_t yyscanner
 
 YY_BUFFER_STATE yy_scan_buffer ( char *base, yy_size_t size , yyscan_t yyscanner );
 YY_BUFFER_STATE yy_scan_string ( const char *yy_str , yyscan_t yyscanner );
-YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, yy_size_t len , yyscan_t yyscanner );
+YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, int len , yyscan_t yyscanner );
 
 void *yyalloc ( yy_size_t , yyscan_t yyscanner );
 void *yyrealloc ( void *, yy_size_t , yyscan_t yyscanner );
@@ -570,7 +569,7 @@ static void yynoreturn yy_fatal_error ( const char* msg , yyscan_t yyscanner );
  */
 #define YY_DO_BEFORE_ACTION \
 	yyg->yytext_ptr = yy_bp; \
-	yyleng = (yy_size_t) (yy_cp - yy_bp); \
+	yyleng = (int) (yy_cp - yy_bp); \
 	yyg->yy_hold_char = *yy_cp; \
 	*yy_cp = '\0'; \
 	yyg->yy_c_buf_p = yy_cp;
@@ -1080,10 +1079,10 @@ static void processInvalidToken(yyscan_t scanner);
 static bool yy_has_state(yyscan_t scanner);
 }
 
-#line 1083 "flex-chpl-lib.cpp"
+#line 1082 "flex-chpl-lib.cpp"
 /* hex float literals, have decimal exponents indicating the power of 2 */
 
-#line 1086 "flex-chpl-lib.cpp"
+#line 1085 "flex-chpl-lib.cpp"
 
 #define INITIAL 0
 #define externmode 1
@@ -1111,8 +1110,8 @@ struct yyguts_t
     size_t yy_buffer_stack_max; /**< capacity of stack. */
     YY_BUFFER_STATE * yy_buffer_stack; /**< Stack as an array. */
     char yy_hold_char;
-    yy_size_t yy_n_chars;
-    yy_size_t yyleng_r;
+    int yy_n_chars;
+    int yyleng_r;
     char *yy_c_buf_p;
     int yy_init;
     int yy_start;
@@ -1169,7 +1168,7 @@ FILE *yyget_out ( yyscan_t yyscanner );
 
 void yyset_out  ( FILE * _out_str , yyscan_t yyscanner );
 
-			yy_size_t yyget_leng ( yyscan_t yyscanner );
+			int yyget_leng ( yyscan_t yyscanner );
 
 char *yyget_text ( yyscan_t yyscanner );
 
@@ -1254,7 +1253,7 @@ static int input ( yyscan_t yyscanner );
 	if ( YY_CURRENT_BUFFER_LVALUE->yy_is_interactive ) \
 		{ \
 		int c = '*'; \
-		yy_size_t n; \
+		int n; \
 		for ( n = 0; n < max_size && \
 			     (c = getc( yyin )) != EOF && c != '\n'; ++n ) \
 			buf[n] = (char) c; \
@@ -1373,7 +1372,7 @@ YY_DECL
 #line 114 "chpl.lex"
 
 
-#line 1376 "flex-chpl-lib.cpp"
+#line 1375 "flex-chpl-lib.cpp"
 
 	while ( /*CONSTCOND*/1 )		/* loops until end-of-file is reached */
 		{
@@ -2378,7 +2377,7 @@ YY_RULE_SETUP
 #line 330 "chpl.lex"
 ECHO;
 	YY_BREAK
-#line 2381 "flex-chpl-lib.cpp"
+#line 2380 "flex-chpl-lib.cpp"
 case YY_STATE_EOF(INITIAL):
 case YY_STATE_EOF(externmode):
 	yyterminate();
@@ -2567,7 +2566,7 @@ static int yy_get_next_buffer (yyscan_t yyscanner)
 
 	else
 		{
-			yy_size_t num_to_read =
+			int num_to_read =
 			YY_CURRENT_BUFFER_LVALUE->yy_buf_size - number_to_move - 1;
 
 		while ( num_to_read <= 0 )
@@ -2581,7 +2580,7 @@ static int yy_get_next_buffer (yyscan_t yyscanner)
 
 			if ( b->yy_is_our_buffer )
 				{
-				yy_size_t new_size = b->yy_buf_size * 2;
+				int new_size = b->yy_buf_size * 2;
 
 				if ( new_size <= 0 )
 					b->yy_buf_size += b->yy_buf_size / 8;
@@ -2639,7 +2638,7 @@ static int yy_get_next_buffer (yyscan_t yyscanner)
 
 	if ((yyg->yy_n_chars + number_to_move) > YY_CURRENT_BUFFER_LVALUE->yy_buf_size) {
 		/* Extend the array by 50%, plus the number we really need. */
-		yy_size_t new_size = yyg->yy_n_chars + number_to_move + (yyg->yy_n_chars >> 1);
+		int new_size = yyg->yy_n_chars + number_to_move + (yyg->yy_n_chars >> 1);
 		YY_CURRENT_BUFFER_LVALUE->yy_ch_buf = (char *) yyrealloc(
 			(void *) YY_CURRENT_BUFFER_LVALUE->yy_ch_buf, (yy_size_t) new_size , yyscanner );
 		if ( ! YY_CURRENT_BUFFER_LVALUE->yy_ch_buf )
@@ -2746,7 +2745,7 @@ static int yy_get_next_buffer (yyscan_t yyscanner)
 
 		else
 			{ /* need more input */
-			yy_size_t offset = yyg->yy_c_buf_p - yyg->yytext_ptr;
+			int offset = (int) (yyg->yy_c_buf_p - yyg->yytext_ptr);
 			++yyg->yy_c_buf_p;
 
 			switch ( yy_get_next_buffer( yyscanner ) )
@@ -3124,12 +3123,12 @@ YY_BUFFER_STATE yy_scan_string (const char * yystr , yyscan_t yyscanner)
  * @param yyscanner The scanner object.
  * @return the newly allocated buffer state object.
  */
-YY_BUFFER_STATE yy_scan_bytes  (const char * yybytes, yy_size_t  _yybytes_len , yyscan_t yyscanner)
+YY_BUFFER_STATE yy_scan_bytes  (const char * yybytes, int  _yybytes_len , yyscan_t yyscanner)
 {
 	YY_BUFFER_STATE b;
 	char *buf;
 	yy_size_t n;
-	yy_size_t i;
+	int i;
     
 	/* Get memory for full buffer, including space for trailing EOB's. */
 	n = (yy_size_t) (_yybytes_len + 2);
@@ -3214,7 +3213,7 @@ static void yynoreturn yy_fatal_error (const char* msg , yyscan_t yyscanner)
 	do \
 		{ \
 		/* Undo effects of setting up yytext. */ \
-        yy_size_t yyless_macro_arg = (n); \
+        int yyless_macro_arg = (n); \
         YY_LESS_LINENO(yyless_macro_arg);\
 		yytext[yyleng] = yyg->yy_hold_char; \
 		yyg->yy_c_buf_p = yytext + yyless_macro_arg; \
@@ -3282,7 +3281,7 @@ FILE *yyget_out  (yyscan_t yyscanner)
 /** Get the length of the current token.
  * @param yyscanner The scanner object.
  */
-yy_size_t yyget_leng  (yyscan_t yyscanner)
+int yyget_leng  (yyscan_t yyscanner)
 {
     struct yyguts_t * yyg = (struct yyguts_t*)yyscanner;
     return yyleng;
diff --git a/frontend/lib/parsing/flex-chpl-lib.h b/frontend/lib/parsing/flex-chpl-lib.h
index a3513a78e7b2..f6fbf73d4e42 100644
--- a/frontend/lib/parsing/flex-chpl-lib.h
+++ b/frontend/lib/parsing/flex-chpl-lib.h
@@ -285,7 +285,6 @@ 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;
@@ -399,7 +398,7 @@ struct yy_buffer_state
 	/* Number of characters read into yy_ch_buf, not including EOB
 	 * characters.
 	 */
-	yy_size_t yy_n_chars;
+	int yy_n_chars;
 
 	/* Whether we "own" the buffer - i.e., we know we created it,
 	 * and can realloc() it to grow it, and should free() it to
@@ -443,7 +442,7 @@ void yypop_buffer_state ( yyscan_t yyscanner );
 
 YY_BUFFER_STATE yy_scan_buffer ( char *base, yy_size_t size , yyscan_t yyscanner );
 YY_BUFFER_STATE yy_scan_string ( const char *yy_str , yyscan_t yyscanner );
-YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, yy_size_t len , yyscan_t yyscanner );
+YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, int len , yyscan_t yyscanner );
 
 void *yyalloc ( yy_size_t , yyscan_t yyscanner );
 void *yyrealloc ( void *, yy_size_t , yyscan_t yyscanner );
@@ -497,7 +496,7 @@ FILE *yyget_out ( yyscan_t yyscanner );
 
 void yyset_out  ( FILE * _out_str , yyscan_t yyscanner );
 
-			yy_size_t yyget_leng ( yyscan_t yyscanner );
+			int yyget_leng ( yyscan_t yyscanner );
 
 char *yyget_text ( yyscan_t yyscanner );
 
@@ -731,6 +730,6 @@ extern int yylex \
 #line 330 "chpl.lex"
 
 
-#line 734 "flex-chpl-lib.h"
+#line 733 "flex-chpl-lib.h"
 #undef yychpl_IN_HEADER
 #endif /* yychpl_HEADER_H */