diff --git a/build-aux/configure-lib.sh b/build-aux/configure-lib.sh
index 1b30c4dc..84e1283e 100644
--- a/build-aux/configure-lib.sh
+++ b/build-aux/configure-lib.sh
@@ -1,7 +1,7 @@
 #! /bin/sh
 
 # GNU Mes --- Maxwell Equations of Software
-# Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+# Copyright © 2019, 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 #
 # This file is part of GNU Mes.
 #
@@ -36,6 +36,7 @@ lib/mes/oputs.c
 
 if test $mes_libc = mes; then
     libc_mini_shared_SOURCES="$libc_mini_shared_SOURCES
+lib/mes/globals.c
 lib/$mes_kernel/$mes_cpu-mes-$compiler/mini.c
 lib/stdlib/exit.c
 lib/stdlib/puts.c
@@ -77,6 +78,7 @@ lib/mes/mini-write.c
 fi
 
 libmescc_SOURCES="
+lib/mes/globals.c
 lib/linux/$mes_cpu-mes-$compiler/syscall-internal.c
 lib/mes/div.c
 "
diff --git a/build-aux/test-c.sh b/build-aux/test-c.sh
index 5d7875f7..723764cb 100755
--- a/build-aux/test-c.sh
+++ b/build-aux/test-c.sh
@@ -47,7 +47,7 @@ then
 fi
 
 if [ -z "${i/[012][0-9]-*/}" ]; then
-    LIBS="${MES_CHECKING_BUILTIN_LIBS}"
+    LIBS="${MES_CHECKING_BUILTIN_LIBS} -l c-mini"
 elif [ -z "${i/[34][0-9]-*/}" ]; then
     LIBS="-l c-mini ${MES_CHECKING_BUILTIN_LIBS} -l c-mini"
 elif [ -z "${i/[78][0-9a-z]-*/}" ]; then
diff --git a/include/errno.h b/include/errno.h
index 7ac1ebe9..b191c410 100644
--- a/include/errno.h
+++ b/include/errno.h
@@ -1,6 +1,6 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
- * Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2017,2018,2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
  *
  * This file is part of GNU Mes.
  *
@@ -31,10 +31,9 @@
 #ifndef __MES_ERRNO_T
 #define __MES_ERRNO_T 1
 typedef int error_t;
-int errno;
 #endif // !__MES_ERRNO_T
 
-int errno;
+extern int errno;
 #define ENOENT   2
 #define EINTR    4
 #define EIO      5
@@ -58,8 +57,8 @@ int errno;
 #define ERANGE  34
 
 #define ENAMETOOLONG 36
-#define ENOSYS 38
-#define ELOOP  40
+#define ENOSYS  38
+#define ELOOP   40
 
 #if !__MESC__
 //extern char const *const sys_errlist[];
diff --git a/include/mes/lib-mini.h b/include/mes/lib-mini.h
index 4cc8d96d..2874d527 100644
--- a/include/mes/lib-mini.h
+++ b/include/mes/lib-mini.h
@@ -1,6 +1,6 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
- * Copyright © 2016,2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2016,2017,2018,2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
  *
  * This file is part of GNU Mes.
  *
@@ -40,10 +40,10 @@
 #define STDERR 2
 #endif
 
-char **environ;
-int __stdin;
-int __stdout;
-int __stderr;
+extern char **environ;
+extern int __stdin;
+extern int __stdout;
+extern int __stderr;
 
 int eputs (char const *s);
 int puts (char const *s);
@@ -87,7 +87,7 @@ typedef long ssize_t;
 #ifndef __MES_ERRNO_T
 #define __MES_ERRNO_T 1
 typedef int error_t;
-int errno;
+extern int errno;
 #endif // !__MES_ERRNO_T
 
 size_t strlen (char const *s);
diff --git a/include/setjmp.h b/include/setjmp.h
index a725bb19..a283cd61 100644
--- a/include/setjmp.h
+++ b/include/setjmp.h
@@ -43,12 +43,6 @@ typedef struct
 #endif
 typedef __jmp_buf jmp_buf[1];
 
-#if __MESC__
-__jmp_buf buf[1];
-#else
-jmp_buf buf;
-#endif
-
 void longjmp (jmp_buf env, int val);
 int setjmp (jmp_buf env);
 
diff --git a/lib/mes/eputs.c b/lib/mes/eputs.c
index 4ffcbc96..26bb3e01 100644
--- a/lib/mes/eputs.c
+++ b/lib/mes/eputs.c
@@ -18,7 +18,7 @@
  * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <mes/lib.h>
+#include <mes/lib-mini.h>
 #include <string.h>
 
 int
diff --git a/lib/mes/globals.c b/lib/mes/globals.c
new file mode 100644
index 00000000..f5c63e3f
--- /dev/null
+++ b/lib/mes/globals.c
@@ -0,0 +1,27 @@
+/*
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <mes/lib-mini.h>
+
+int errno;
+char **environ;
+int __stdin;
+int __stdout;
+int __stderr;
diff --git a/lib/mes/oputs.c b/lib/mes/oputs.c
index 3d1e4382..cc00528c 100644
--- a/lib/mes/oputs.c
+++ b/lib/mes/oputs.c
@@ -18,7 +18,7 @@
  * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <mes/lib.h>
+#include <mes/lib-mini.h>
 #include <string.h>
 
 int