diff --git a/frontends/amiga/search.h b/frontends/amiga/search.h
index f30352cd5..1815ef954 100755
--- a/frontends/amiga/search.h
+++ b/frontends/amiga/search.h
@@ -22,7 +22,7 @@
 struct gui_search_table;
 struct gui_window;
 
-struct gui_search_table *amiga_search_table;
+extern struct gui_search_table *amiga_search_table;
 
 /**
  * Change the displayed search status.
diff --git a/frontends/atari/bitmap.h b/frontends/atari/bitmap.h
index b0fa18069..72bad555e 100644
--- a/frontends/atari/bitmap.h
+++ b/frontends/atari/bitmap.h
@@ -54,7 +54,7 @@
 */
 #define MFDB_SIZE( bpp, stride, h ) ( ((stride >> 3) * h) * bpp )
 
-struct gui_bitmap_table *atari_bitmap_table;
+extern struct gui_bitmap_table *atari_bitmap_table;
 
 struct bitmap {
 	int width;
diff --git a/frontends/atari/encoding.h b/frontends/atari/encoding.h
index 784aa8273..53db7b78b 100644
--- a/frontends/atari/encoding.h
+++ b/frontends/atari/encoding.h
@@ -25,7 +25,7 @@
 
 #include "utils/utf8.h"
 
-struct gui_utf8_table *atari_utf8_table;
+extern struct gui_utf8_table *atari_utf8_table;
 
 nserror utf8_to_local_encoding(const char *string, size_t len, char **result);
 nserror utf8_from_local_encoding(const char *string, size_t len, char **result);
diff --git a/frontends/atari/file.h b/frontends/atari/file.h
index b368567c7..3e568834b 100644
--- a/frontends/atari/file.h
+++ b/frontends/atari/file.h
@@ -21,7 +21,7 @@
 
 #include "utils/file.h"
 
-struct gui_file_table *atari_file_table;
+extern struct gui_file_table *atari_file_table;
 
 
 #endif /* FILE_C_INCLUDED */
diff --git a/frontends/atari/font.h b/frontends/atari/font.h
index a01d000c0..c0eb99dcd 100644
--- a/frontends/atari/font.h
+++ b/frontends/atari/font.h
@@ -19,7 +19,7 @@
 #ifndef NS_ATARI_FONT_H
 #define NS_ATARI_FONT_H
 
-struct gui_layout_table *atari_layout_table;
+extern struct gui_layout_table *atari_layout_table;
 
 #endif /* NETSURF_FB_FONT_H */
 
diff --git a/frontends/atari/search.h b/frontends/atari/search.h
index 04dfed4eb..adac62652 100644
--- a/frontends/atari/search.h
+++ b/frontends/atari/search.h
@@ -43,7 +43,7 @@ typedef struct s_search_form_session * SEARCH_FORM_SESSION;
 struct s_search_form_session * nsatari_search_session_create(OBJECT * obj,
 		struct gui_window *gw);
 
-struct gui_search_table *atari_search_table;
+extern struct gui_search_table *atari_search_table;
 
 void nsatari_search_session_destroy(struct s_search_form_session *s);
 void nsatari_search_perform(struct s_search_form_session *s, OBJECT *obj,
diff --git a/frontends/framebuffer/fetch.h b/frontends/framebuffer/fetch.h
index 718b08300..d00f3aa21 100644
--- a/frontends/framebuffer/fetch.h
+++ b/frontends/framebuffer/fetch.h
@@ -20,6 +20,6 @@
 #ifndef NETSURF_FB_FETCH_H
 #define NETSURF_FB_FETCH_H
 
-struct gui_fetch_table *framebuffer_fetch_table;
+extern struct gui_fetch_table *framebuffer_fetch_table;
 
 #endif
diff --git a/frontends/gtk/download.h b/frontends/gtk/download.h
index 0b1097655..b720650ca 100644
--- a/frontends/gtk/download.h
+++ b/frontends/gtk/download.h
@@ -24,7 +24,7 @@
 /**
  * download operation table for gtk
  */
-struct gui_download_table *nsgtk_download_table;
+extern struct gui_download_table *nsgtk_download_table;
 
 /**
  * Initialise download window ready for use.
diff --git a/frontends/gtk/fetch.h b/frontends/gtk/fetch.h
index a095adbf9..9175ccdf2 100644
--- a/frontends/gtk/fetch.h
+++ b/frontends/gtk/fetch.h
@@ -19,7 +19,7 @@
 #ifndef NETSURF_GTK_FETCH_H
 #define NETSURF_GTK_FETCH_H
 
-struct gui_fetch_table *nsgtk_fetch_table;
+extern struct gui_fetch_table *nsgtk_fetch_table;
 
 void gtk_fetch_filetype_init(const char *mimefile);
 void gtk_fetch_filetype_fin(void);
diff --git a/frontends/gtk/search.h b/frontends/gtk/search.h
index dd8c60d0f..b2162b805 100644
--- a/frontends/gtk/search.h
+++ b/frontends/gtk/search.h
@@ -19,7 +19,7 @@
 #ifndef _NETSURF_GTK_SEARCH_H_
 #define _NETSURF_GTK_SEARCH_H_
 
-struct gui_search_table *nsgtk_search_table;
+extern struct gui_search_table *nsgtk_search_table;
 
 struct nsgtk_scaffolding;
 
diff --git a/frontends/gtk/selection.h b/frontends/gtk/selection.h
index 6463692cf..07716a0d9 100644
--- a/frontends/gtk/selection.h
+++ b/frontends/gtk/selection.h
@@ -19,6 +19,6 @@
 #ifndef GTK_SELECTION_H
 #define GTK_SELECTION_H
 
-struct gui_clipboard_table *nsgtk_clipboard_table;
+extern struct gui_clipboard_table *nsgtk_clipboard_table;
 
 #endif
diff --git a/frontends/monkey/fetch.h b/frontends/monkey/fetch.h
index f146e2ef8..2881e92c5 100644
--- a/frontends/monkey/fetch.h
+++ b/frontends/monkey/fetch.h
@@ -19,6 +19,6 @@
 #ifndef NS_MONKEY_FETCH_H
 #define NS_MONKEY_FETCH_H
 
-struct gui_fetch_table *monkey_fetch_table;
+extern struct gui_fetch_table *monkey_fetch_table;
 
 #endif /* NS_MONKEY_FETCH_H */
diff --git a/frontends/riscos/bitmap.h b/frontends/riscos/bitmap.h
index 3aca30de6..f66ebb317 100644
--- a/frontends/riscos/bitmap.h
+++ b/frontends/riscos/bitmap.h
@@ -25,7 +25,7 @@ struct hlcache_handle;
 struct bitmap;
 
 /** bitmap operations table */
-struct gui_bitmap_table *riscos_bitmap_table;
+extern struct gui_bitmap_table *riscos_bitmap_table;
 
 /** save with full alpha channel (if not opaque) */
 #define BITMAP_SAVE_FULL_ALPHA	(1 << 0)
diff --git a/frontends/riscos/font.h b/frontends/riscos/font.h
index a29bad83a..5a82f63ee 100644
--- a/frontends/riscos/font.h
+++ b/frontends/riscos/font.h
@@ -26,7 +26,7 @@
 #include <rufl.h>
 
 struct plot_font_style;
-struct gui_layout_table *riscos_layout_table;
+extern struct gui_layout_table *riscos_layout_table;
 
 /** desktop font, size and style being used */
 extern char ro_gui_desktop_font_family[];
diff --git a/frontends/riscos/gui.h b/frontends/riscos/gui.h
index 65c85f92a..d4ff9ce62 100644
--- a/frontends/riscos/gui.h
+++ b/frontends/riscos/gui.h
@@ -167,7 +167,7 @@ nserror riscos_schedule(int t, void (*callback)(void *p), void *p);
 /* in search.c */
 void ro_gui_search_init(void);
 void ro_gui_search_prepare(struct browser_window *g);
-struct gui_search_table *riscos_search_table;
+extern struct gui_search_table *riscos_search_table;
 
 /* in print.c */
 void ro_gui_print_init(void);
diff --git a/frontends/riscos/textselection.h b/frontends/riscos/textselection.h
index 400e3dd26..0d7cc169b 100644
--- a/frontends/riscos/textselection.h
+++ b/frontends/riscos/textselection.h
@@ -25,7 +25,7 @@
 
 #include "oslib/wimp.h"
 
-struct gui_clipboard_table *riscos_clipboard_table;
+extern struct gui_clipboard_table *riscos_clipboard_table;
 
 void gui_start_selection(struct gui_window *g);
 
diff --git a/frontends/riscos/ucstables.h b/frontends/riscos/ucstables.h
index e5d838249..31db5d882 100644
--- a/frontends/riscos/ucstables.h
+++ b/frontends/riscos/ucstables.h
@@ -21,7 +21,7 @@
  * This is only used if nothing claims Service_International,8
  */
 
-struct gui_utf8_table *riscos_utf8_table;
+extern struct gui_utf8_table *riscos_utf8_table;
 
 nserror utf8_to_local_encoding(const char *string, size_t len, char **result);
 nserror utf8_from_local_encoding(const char *string, size_t len, char **result);
diff --git a/frontends/windows/bitmap.h b/frontends/windows/bitmap.h
index c723159e1..c57061d77 100644
--- a/frontends/windows/bitmap.h
+++ b/frontends/windows/bitmap.h
@@ -20,7 +20,7 @@
 #ifndef _NETSURF_WINDOWS_BITMAP_H_
 #define _NETSURF_WINDOWS_BITMAP_H_
 
-struct gui_bitmap_table *win32_bitmap_table;
+extern struct gui_bitmap_table *win32_bitmap_table;
 
 struct bitmap {
 	HBITMAP windib;
diff --git a/frontends/windows/clipboard.h b/frontends/windows/clipboard.h
index c707c2437..92f096b8e 100644
--- a/frontends/windows/clipboard.h
+++ b/frontends/windows/clipboard.h
@@ -22,6 +22,6 @@
 /**
  * The clipboard operation function table for win32
  */
-struct gui_clipboard_table *win32_clipboard_table;
+extern struct gui_clipboard_table *win32_clipboard_table;
 
 #endif
diff --git a/frontends/windows/fetch.h b/frontends/windows/fetch.h
index 20984f14a..e85402ac3 100644
--- a/frontends/windows/fetch.h
+++ b/frontends/windows/fetch.h
@@ -22,7 +22,7 @@
 /**
  * win32 API fetch operation table
  */
-struct gui_fetch_table *win32_fetch_table;
+extern struct gui_fetch_table *win32_fetch_table;
 
 /**
  * Translate resource to win32 resource data.
diff --git a/frontends/windows/file.h b/frontends/windows/file.h
index 5262dde2c..19dfba3b1 100644
--- a/frontends/windows/file.h
+++ b/frontends/windows/file.h
@@ -24,6 +24,6 @@
 #ifndef _NETSURF_WINDOWS_FILE_H_
 #define _NETSURF_WINDOWS_FILE_H_
 
-struct gui_file_table *win32_file_table;
+extern struct gui_file_table *win32_file_table;
 
 #endif 
diff --git a/frontends/windows/font.h b/frontends/windows/font.h
index ec2c262ff..8219e4c76 100644
--- a/frontends/windows/font.h
+++ b/frontends/windows/font.h
@@ -35,8 +35,8 @@ struct font_desc {
     const char *encoding;
 };
 
-struct gui_layout_table *win32_layout_table;
-struct gui_utf8_table *win32_utf8_table;
+extern struct gui_layout_table *win32_layout_table;
+extern struct gui_utf8_table *win32_utf8_table;
 
 /**
  * convert from utf-8 to win32 font encoding.
diff --git a/utils/file.h b/utils/file.h
index 5ee13b5aa..0282c350e 100644
--- a/utils/file.h
+++ b/utils/file.h
@@ -117,7 +117,7 @@ struct gui_file_table {
 };
 
 /** Default (posix) file operation table. */
-struct gui_file_table *default_file_table;
+extern struct gui_file_table *default_file_table;
 
 /**
  * Generate a path from one or more component elemnts.