diff --git a/ChangeLog b/ChangeLog
index 485842f61f..80be0365f3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2004-08-08  Sven Neumann  <sven@gimp.org>
+
+	* plug-ins/script-fu/siod-wrapper.[ch] (siod_output_string): use
+	g_strdup_vprintf() instead of guessing the string length. Also
+	declare the function using G_GNUC_PRINTF().
+
 2004-08-08  Bill Skaggs <weskaggs@primate.ucdavis.edu>
 
 	* plug-ins/ifscompose/README.ifscompose: fix out of date info,
diff --git a/plug-ins/script-fu/scheme-wrapper.c b/plug-ins/script-fu/scheme-wrapper.c
index 6e79c3072f..7406a7e843 100644
--- a/plug-ins/script-fu/scheme-wrapper.c
+++ b/plug-ins/script-fu/scheme-wrapper.c
@@ -112,31 +112,28 @@ siod_get_success_msg (void)
 }
 
 void
-siod_output_string (FILE *fp, char *string, ...)
+siod_output_string (FILE        *fp,
+                    const gchar *format,
+                    ...)
 {
-  gint buff_len;
-  gchar *buff;
-  va_list args;
+  gchar   *buf;
+  va_list  args;
 
-  /* Ensure plenty of room in case string contains %-style format codes */
-  buff_len = strlen (string) * 2;
-  buff = g_malloc (buff_len);
-  if (buff == NULL)
-     return;	/* Should "No memory" be output here? */
-
-  va_start (args, string);
-  g_vsnprintf (buff, buff_len, string, args);
+  va_start (args, format);
+  buf = g_strdup_vprintf (format, args);
   va_end (args);
 
   if (siod_console_mode && fp == stdout)
-     script_fu_output_to_console (buff);
+    {
+      script_fu_output_to_console (buf);
+    }
   else
-  {
-     fprintf (fp, buff);
-     fflush (fp);
-  }
+    {
+      fprintf (fp, buf);
+      fflush (fp);
+    }
 
-  g_free (buff);
+  g_free (buf);
 }
 
 
diff --git a/plug-ins/script-fu/scheme-wrapper.h b/plug-ins/script-fu/scheme-wrapper.h
index a5b5a1293b..8d508c9249 100644
--- a/plug-ins/script-fu/scheme-wrapper.h
+++ b/plug-ins/script-fu/scheme-wrapper.h
@@ -35,7 +35,9 @@ void          siod_print_welcome     (void);
 const gchar * siod_get_error_msg     (void);
 const gchar * siod_get_success_msg   (void);
 
-void          siod_output_string     (FILE *fp, char *string, ...);
+void          siod_output_string     (FILE        *fp,
+                                      const gchar *format,
+                                      ...) G_GNUC_PRINTF (2, 3);
 
 /* if the return value is 0, success. error otherwise. */
 gint          siod_interpret_string  (const gchar *expr);
diff --git a/plug-ins/script-fu/siod-wrapper.c b/plug-ins/script-fu/siod-wrapper.c
index 6e79c3072f..7406a7e843 100644
--- a/plug-ins/script-fu/siod-wrapper.c
+++ b/plug-ins/script-fu/siod-wrapper.c
@@ -112,31 +112,28 @@ siod_get_success_msg (void)
 }
 
 void
-siod_output_string (FILE *fp, char *string, ...)
+siod_output_string (FILE        *fp,
+                    const gchar *format,
+                    ...)
 {
-  gint buff_len;
-  gchar *buff;
-  va_list args;
+  gchar   *buf;
+  va_list  args;
 
-  /* Ensure plenty of room in case string contains %-style format codes */
-  buff_len = strlen (string) * 2;
-  buff = g_malloc (buff_len);
-  if (buff == NULL)
-     return;	/* Should "No memory" be output here? */
-
-  va_start (args, string);
-  g_vsnprintf (buff, buff_len, string, args);
+  va_start (args, format);
+  buf = g_strdup_vprintf (format, args);
   va_end (args);
 
   if (siod_console_mode && fp == stdout)
-     script_fu_output_to_console (buff);
+    {
+      script_fu_output_to_console (buf);
+    }
   else
-  {
-     fprintf (fp, buff);
-     fflush (fp);
-  }
+    {
+      fprintf (fp, buf);
+      fflush (fp);
+    }
 
-  g_free (buff);
+  g_free (buf);
 }
 
 
diff --git a/plug-ins/script-fu/siod-wrapper.h b/plug-ins/script-fu/siod-wrapper.h
index a5b5a1293b..8d508c9249 100644
--- a/plug-ins/script-fu/siod-wrapper.h
+++ b/plug-ins/script-fu/siod-wrapper.h
@@ -35,7 +35,9 @@ void          siod_print_welcome     (void);
 const gchar * siod_get_error_msg     (void);
 const gchar * siod_get_success_msg   (void);
 
-void          siod_output_string     (FILE *fp, char *string, ...);
+void          siod_output_string     (FILE        *fp,
+                                      const gchar *format,
+                                      ...) G_GNUC_PRINTF (2, 3);
 
 /* if the return value is 0, success. error otherwise. */
 gint          siod_interpret_string  (const gchar *expr);