diff --git a/missing/explicit_bzero.c b/missing/explicit_bzero.c
index baa4624d13..bf493c18ac 100644
--- a/missing/explicit_bzero.c
+++ b/missing/explicit_bzero.c
@@ -23,6 +23,7 @@
 # define FUNC_UNOPTIMIZED(x) x
 #endif
 
+#undef explicit_bzero
 #ifndef HAVE_EXPLICIT_BZERO
  #ifdef HAVE_MEMSET_S
 void