--- ./units.h	2017-02-09 21:43:12.000000000 +0000
+++ ../units.h	2018-03-21 20:22:04.544833906 +0000
@@ -54,7 +54,7 @@
 #  ifdef NO_STRCHR
 #    define strchr(a,b) index((a),(b))
 #  else
-     char *strchr();
+     char __attribute__((overloadable)) *strchr();
 #  endif
 #endif /* !strchr */