diff --git a/newlib/libc/sys/arm/aeabi_atexit.c b/newlib/libc/sys/arm/aeabi_atexit.c
index 4b600e250..a5626b732 100644
--- a/newlib/libc/sys/arm/aeabi_atexit.c
+++ b/newlib/libc/sys/arm/aeabi_atexit.c
@@ -1,5 +1,8 @@
 #include <stdlib.h>
 
+/* forward declaration */
+extern int __cxa_atexit (void (*) (void *), void *, void *);
+
 /* Register a function to be called by exit or when a shared library
    is unloaded.  This routine is like __cxa_atexit, but uses the
    calling sequence required by the ARM EABI.  */