diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 12c5b0a8fa2..82ea3c62739 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -11297,12 +11297,11 @@ try_build_id_prefix (const char * prefix, char * filename, const unsigned char *
 {
   char * f = filename;
 
-  f += sprintf (f, prefix);
-  f += sprintf (f, ".build-id/%02x/", (unsigned) *data++);
+  f += sprintf (f, "%s.build-id/%02x/", prefix, (unsigned) *data++);
   id_len --;
   while (id_len --)
     f += sprintf (f, "%02x", (unsigned) *data++);
-  f += sprintf (f, ".debug");
+  strcpy (f, ".debug");
 
   return open_debug_file (filename);
 }