Index: iolib/dofmt.c
===================================================================
--- iolib/dofmt.c	(revision 526a9931ecf963fd88914bbf92cee82eb60a80bd)
+++ iolib/dofmt.c	(revision 7af8be4146b7665a3c5d25c39c1ecc2f3b0ff34f)
@@ -35,5 +35,5 @@
 #define	min(a,b)	((a)<(b)?(a):(b))
 
-int32_t dofmt_(int16_t (*putsub)(), int8_t *format, va_list args)
+int32_t dofmt_(int16_t (*putsub)(int16_t c), int8_t *format, va_list args)
 {
 	register int16_t fcode;
Index: iolib/dofmt.x
===================================================================
--- iolib/dofmt.x	(revision 526a9931ecf963fd88914bbf92cee82eb60a80bd)
+++ iolib/dofmt.x	(revision 7af8be4146b7665a3c5d25c39c1ecc2f3b0ff34f)
@@ -16,3 +16,3 @@
 */
 
-extern	int32_t		dofmt_(int16_t (*putsub)(), int8_t *format, va_list args);
+extern	int32_t		dofmt_(int16_t (*putsub)(int16_t c), int8_t *format, va_list args);
Index: iolib/sprintf.c
===================================================================
--- iolib/sprintf.c	(revision 526a9931ecf963fd88914bbf92cee82eb60a80bd)
+++ iolib/sprintf.c	(revision 7af8be4146b7665a3c5d25c39c1ecc2f3b0ff34f)
@@ -9,5 +9,5 @@
 
 static int8_t	*buff;
-static int16_t spsub(int8_t c);
+static int16_t spsub(int16_t c);
 
 /*
@@ -36,7 +36,6 @@
 */
 
-static int16_t spsub(int8_t c)
+static int16_t spsub(int16_t c)
 {
 	return((*buff++ = c) & 0xFF);
 }
-