diff --git a/istrcmp.c b/istrcmp.c
index dd79811..1df7358 100644
--- a/istrcmp.c
+++ b/istrcmp.c
@@ -1,6 +1,8 @@
-/*
+/*-
+ * SPDX-License-Identifier: MIT-open-group
+ *
  * Copyright (c) 1991-1994  Sony Corporation
- * 
+ *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
@@ -8,10 +10,10 @@
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
- * 
+ *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
- * 
+ *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
@@ -19,41 +21,33 @@
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- * 
+ *
  * Except as contained in this notice, the name of Sony Corporation
  * shall not be used in advertising or otherwise to promote the sale, use
  * or other dealings in this Software without prior written authorization
  * from Sony Corporation.
- *
  */
 
-/*
- * $SonyRCSfile: istrcmp.c,v $  
- * $SonyRevision: 1.1 $ 
- * $SonyDate: 1994/06/03 08:01:55 $
- */
-
-
-
 #include "sj_rename.h"
-#include "sj_typedef.h"
+
 #include "const.h"
+#include "sj_typedef.h"
 
-Int	istrcmp(yomip, idxp, ylen, ilen)
-Reg1	Uchar	*yomip;
-Reg2	Uchar	*idxp;
-Reg3	Int	ylen;
-Reg4	Int	ilen;
+Int
+istrcmp(Uchar *yomip, Uchar *idxp, Int ylen, Int ilen)
 {
-	for (;;) {
+	while (1) {
+		if ((ilen | ylen) == 0)
+			return MATCH;
 
-		if ((ilen | ylen) == 0) return MATCH;
+		if (ilen == 0)
+			return UNDER;
 
-		if (ilen == 0) return UNDER;
+		if ((ylen == 0) || (*yomip < *idxp))
+			return OVER;
 
-		if ((ylen == 0) || (*yomip < *idxp)) return OVER;
-
-		if (*yomip > *idxp) return UNDER;
+		if (*yomip > *idxp)
+			return UNDER;
 
 		yomip++;
 		idxp++;
@@ -61,4 +55,3 @@ Reg4	Int	ilen;
 		ilen--;
 	}
 }
-