diff --git a/devel/gconfmm26/files/patch-gconf_gconfmm_callback.h b/devel/gconfmm26/files/patch-gconf_gconfmm_callback.h
new file mode 100644
index 000000000000..e05da1ce63f6
--- /dev/null
+++ b/devel/gconfmm26/files/patch-gconf_gconfmm_callback.h
@@ -0,0 +1,13 @@
+--- gconf/gconfmm/callback.h.orig	2021-08-02 02:49:39 UTC
++++ gconf/gconfmm/callback.h
+@@ -22,10 +22,7 @@
+ #ifndef GCONFMM_CALLBACK_H
+ #define GCONFMM_CALLBACK_H
+ 
+-extern "C"
+-{
+ #include <gconf/gconf-client.h>
+-}
+ 
+ #include <glibmm/object.h>
+ #include <gconfmm/entry.h>