diff --git a/libs/sofia-sip/libsofia-sip-ua/su/sofia-sip/heap.h b/libs/sofia-sip/libsofia-sip-ua/su/sofia-sip/heap.h
index 50007ce684..25142795a7 100644
--- a/libs/sofia-sip/libsofia-sip-ua/su/sofia-sip/heap.h
+++ b/libs/sofia-sip/libsofia-sip-ua/su/sofia-sip/heap.h
@@ -319,9 +319,6 @@ scope void prefix##_swap(void *h, size_t a, size_t b) \
   type *_heap = h; type _swap = _heap[a]; \
   set(_heap, a, _heap[b]); set(_heap, b, _swap); \
 } \
-void su_smoothsort(void *base, size_t r0, size_t N,		\
-		   int (*less)(void *base, size_t a, size_t b), \
-		   void (*swap)(void *base, size_t a, size_t b));	\
 scope void prefix##sort(heaptype h) \
 { \
   struct prefix##priv { size_t _size, _used; type _heap[1];}; \
@@ -331,4 +328,14 @@ scope void prefix##sort(heaptype h) \
 } \
 extern int const prefix##dummy_heap
 
+#include <sofia-sip/su_types.h>
+
+SOFIA_BEGIN_DECLS
+
+SOFIAPUBFUN void su_smoothsort(void *base, size_t r0, size_t N,
+			       int (*less)(void *base, size_t a, size_t b),
+			       void (*swap)(void *base, size_t a, size_t b));
+
+SOFIA_END_DECLS
+
 #endif /** !defined(SOFIA_SIP_HEAP_H) */