-fno-common

Index: src/make.h
--- src/make.h.orig
+++ src/make.h
@@ -333,7 +333,7 @@ extern int unixy_shell;
 #endif
 #ifdef SET_STACK_SIZE
 # include <sys/resource.h>
-struct rlimit stack_limit;
+extern struct rlimit stack_limit;
 #endif
 
 /* We have to have stdarg.h or varargs.h AND v*printf or doprnt to use
