diff -ur a/asmrun/startup.c b/asmrun/startup.c
--- a/asmrun/startup.c	2017-07-12 17:51:21.000000000 +0200
+++ b/asmrun/startup.c	2020-08-02 14:52:09.585526112 +0200
@@ -44,7 +44,7 @@
 #endif
 
 extern int caml_parser_trace;
-CAMLexport header_t caml_atom_table[256];
+CAMLextern header_t caml_atom_table[256];
 char * caml_code_area_start, * caml_code_area_end;
 
 /* Initialize the atom table and the static data and code area limits. */
diff -ur a/byterun/backtrace.c b/byterun/backtrace.c
--- a/byterun/backtrace.c	2017-07-12 17:51:21.000000000 +0200
+++ b/byterun/backtrace.c	2020-08-02 14:17:15.257475160 +0200
@@ -28,7 +28,7 @@
 #include "caml/fail.h"
 
 /* The table of debug information fragments */
-struct ext_table caml_debug_info;
+extern struct ext_table caml_debug_info;
 
 CAMLexport int32_t caml_backtrace_active = 0;
 CAMLexport int32_t caml_backtrace_pos = 0;
diff -ur a/byterun/caml/intext.h b/byterun/caml/intext.h
--- a/byterun/caml/intext.h	2017-07-12 17:51:21.000000000 +0200
+++ b/byterun/caml/intext.h	2020-08-02 14:13:01.069021621 +0200
@@ -196,7 +196,7 @@
 
 CAMLextern struct code_fragment * caml_extern_find_code(char *addr);
 
-struct ext_table caml_code_fragments_table;
+extern struct ext_table caml_code_fragments_table;
 
 #endif /* CAML_INTERNALS */
 
diff -ur a/byterun/caml/major_gc.h b/byterun/caml/major_gc.h
--- a/byterun/caml/major_gc.h	2017-07-12 17:51:21.000000000 +0200
+++ b/byterun/caml/major_gc.h	2020-08-02 14:11:22.669620273 +0200
@@ -64,9 +64,9 @@
 extern char *caml_gc_sweep_hp;
 
 extern int caml_major_window;
-double caml_major_ring[Max_major_window];
-int caml_major_ring_index;
-double caml_major_work_credit;
+extern double caml_major_ring[Max_major_window];
+extern int caml_major_ring_index;
+extern double caml_major_work_credit;
 extern double caml_gc_clock;
 
 /* [caml_major_gc_hook] is called just between the end of the mark
diff -ur a/byterun/meta.c b/byterun/meta.c
--- a/byterun/meta.c	2017-07-12 17:51:21.000000000 +0200
+++ b/byterun/meta.c	2020-08-02 14:27:09.583859329 +0200
@@ -32,6 +32,8 @@
 #include "caml/prims.h"
 #include "caml/stacks.h"
 
+struct ext_table caml_code_fragments_table;
+
 #ifndef NATIVE_CODE
 
 CAMLprim value caml_get_global_data(value unit)