diff --git a/textio/textioInt.h b/textio/textioInt.h
index 7075a979..81f58fb0 100644
--- a/textio/textioInt.h
+++ b/textio/textioInt.h
@@ -60,7 +60,10 @@ int  TranslateChar();
 char *TxGetLineWPrompt();
 
 #ifdef MAGIC_WRAPPER
-int  Tcl_printf();
+/* tcltk/tclmagic.c has a function implementation prototype mimics vfprintf() mapping
+ * when ifndef MAGIC_WRAPPER
+ */
+extern int Tcl_printf(FILE *fp, const char *fmt, va_list ap);
 #endif
 
 #endif /* _TEXTIOINT_H */
diff --git a/utils/tech.c b/utils/tech.c
index ac470b72..5a371b13 100644
--- a/utils/tech.c
+++ b/utils/tech.c
@@ -56,7 +56,7 @@ static char rcsid[] __attribute__ ((unused)) = "$Header: /usr/cvsroot/magic-8.0/
 #include "plow/plow.h"
 
 /* Cannot include tcltk/tclmagic.h for a clash with utils/magic.h
-extern int Tcl_printf(FILE *, char *, va_list); */
+extern int Tcl_printf(FILE *, const char *, va_list); */
 
 global int  TechFormatVersion;
 global bool TechOverridesDefault;