1 files changed, 4 insertions, 0 deletions
diff --git a/debug.h b/debug.h
index 5c4b19a78b..107ece9ec4 100644
--- a/debug.h
+++ b/debug.h
@@ -29,4 +29,8 @@ int   ruby_debug_print_indent(int level, int debug_level, int indent_level);
 void  ruby_debug_breakpoint(void);
 void  ruby_debug_gc_check_func(void);
 
+#ifdef RUBY_DEBUG_ENV
+void ruby_set_debug_option(const char *str);
+#endif
+
 #endif /* RUBY_DEBUG_H */