Use X extern "C" guards around function declarations for public header
diff --git a/include/X11/extensions/XKBcommon.h b/include/X11/extensions/XKBcommon.h
index 253914c..7f98287 100644
--- a/include/X11/extensions/XKBcommon.h
+++ b/include/X11/extensions/XKBcommon.h
@@ -30,6 +30,7 @@ authorization from the authors.
#include <X11/X.h>
#include <X11/Xdefs.h>
+#include <X11/Xfuncproto.h>
#include <X11/keysymdef.h>
#include <X11/extensions/XKBstrcommon.h>
#include <X11/extensions/XKBgeomcommon.h>
@@ -51,6 +52,8 @@ typedef struct _XkbcDesc {
XkbGeometryPtr geom;
} XkbcDescRec, *XkbcDescPtr;
+_XFUNCPROTOBEGIN
+
extern char *
XkbcKeysymToString(KeySym ks);
@@ -155,4 +158,6 @@ XkbcAtomGetString(Atom atom);
extern Atom
XkbcInternAtom(char *name, Bool onlyIfExists);
+_XFUNCPROTOEND
+
#endif /* _XKBCOMMON_H_ */