diff -up glabels-3.4.1/src/font-history.h.f32 glabels-3.4.1/src/font-history.h
--- glabels-3.4.1/src/font-history.h.f32	2016-03-04 05:01:15.000000000 +0100
+++ glabels-3.4.1/src/font-history.h	2020-02-03 08:41:46.371176433 +0100
@@ -28,7 +28,7 @@
 G_BEGIN_DECLS
 
 
-glFontHistoryModel *gl_font_history;
+extern glFontHistoryModel *gl_font_history;
 
 
 void            gl_font_history_init (void);
diff -up glabels-3.4.1/src/template-history.h.f32 glabels-3.4.1/src/template-history.h
--- glabels-3.4.1/src/template-history.h.f32	2016-03-04 05:01:15.000000000 +0100
+++ glabels-3.4.1/src/template-history.h	2020-02-03 08:42:28.547175850 +0100
@@ -28,7 +28,7 @@
 G_BEGIN_DECLS
 
 
-glTemplateHistoryModel *gl_template_history;
+extern glTemplateHistoryModel *gl_template_history;
 
 
 void            gl_template_history_init (void);