diff --git a/plug-ins/script-fu/tinyscheme/scheme-private.h b/plug-ins/script-fu/tinyscheme/scheme-private.h
index 0a65eae1ae..95b5d248c7 100644
--- a/plug-ins/script-fu/tinyscheme/scheme-private.h
+++ b/plug-ins/script-fu/tinyscheme/scheme-private.h
@@ -171,6 +171,8 @@ gunichar charvalue(pointer p);
 int is_vector(pointer p);
 
 int is_port(pointer p);
+int is_inport(pointer p);
+int is_outport(pointer p);
 
 int is_pair(pointer p);
 pointer pair_car(pointer p);
diff --git a/plug-ins/script-fu/tinyscheme/scheme.h b/plug-ins/script-fu/tinyscheme/scheme.h
index 0e0763c4d1..28932201f8 100644
--- a/plug-ins/script-fu/tinyscheme/scheme.h
+++ b/plug-ins/script-fu/tinyscheme/scheme.h
@@ -247,6 +247,7 @@ typedef struct scheme_registerable
 }
 scheme_registerable;
 
+void scheme_register_foreign_func(scheme * sc, scheme_registerable * sr);
 void scheme_register_foreign_func_list(scheme * sc,
                                       scheme_registerable * list,
                                       int n);