diff --git a/include/mruby.h b/include/mruby.h
index ee23688ff..a0fb07442 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -1271,18 +1271,18 @@ MRB_API void mrb_close(mrb_state *mrb);
 MRB_API void mrb_method_cache_clear(mrb_state *mrb);
 
 /**
- * Check if mrb_open() succeeded
+ * Check if mrb_open() failed
  *
  * @param mrb
  *      Pointer returned from mrb_open() or mrb_open_core().
  * @return
- *      Non-zero if initialization succeeded, 0 if failed.
+ *      Non-zero if initialization failed, 0 if succeeded.
  * @note
  *      mrb_open() may return non-NULL even on failure (with mrb->exc set).
- *      Use this macro to check for success:
+ *      Use this macro to check for failure:
  *      @code
  *      mrb_state *mrb = mrb_open();
- *      if (!MRB_OPEN_SUCCESS(mrb)) {
+ *      if (MRB_OPEN_FAILURE(mrb)) {
  *        if (mrb) {
  *          // Inspect mrb->exc for error details
  *          mrb_close(mrb);
@@ -1291,7 +1291,17 @@ MRB_API void mrb_method_cache_clear(mrb_state *mrb);
  *      }
  *      @endcode
  */
-#define MRB_OPEN_SUCCESS(mrb) ((mrb) && !(mrb)->exc)
+#define MRB_OPEN_FAILURE(mrb) (!(mrb) || (mrb)->exc)
+
+/**
+ * Check if mrb_open() succeeded
+ *
+ * @param mrb
+ *      Pointer returned from mrb_open() or mrb_open_core().
+ * @return
+ *      Non-zero if initialization succeeded, 0 if failed.
+ */
+#define MRB_OPEN_SUCCESS(mrb) (!MRB_OPEN_FAILURE(mrb))
 
 /**
  * The memory allocation function. You can redefine this function for your own allocator.
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c b/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
index c2f736871..b3f1a1db8 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/mrdb.c
@@ -673,7 +673,7 @@ main(int argc, char **argv)
 
  l_restart:
 
-  if (!MRB_OPEN_SUCCESS(mrb)) {
+  if (MRB_OPEN_FAILURE(mrb)) {
     mrb_print_error(mrb);  /* handles NULL */
     mrb_close(mrb);        /* handles NULL */
     return EXIT_FAILURE;
diff --git a/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c b/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
index c26dcfdd3..35901816c 100644
--- a/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
+++ b/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
@@ -475,7 +475,7 @@ main(int argc, char **argv)
 
   /* new interpreter instance */
   mrb = mrb_open();
-  if (!MRB_OPEN_SUCCESS(mrb)) {
+  if (MRB_OPEN_FAILURE(mrb)) {
     mrb_print_error(mrb);  /* handles NULL */
     mrb_close(mrb);        /* handles NULL */
     return EXIT_FAILURE;
diff --git a/mrbgems/mruby-bin-mruby/tools/mruby/mruby.c b/mrbgems/mruby-bin-mruby/tools/mruby/mruby.c
index fc56900c3..b5201d1ea 100644
--- a/mrbgems/mruby-bin-mruby/tools/mruby/mruby.c
+++ b/mrbgems/mruby-bin-mruby/tools/mruby/mruby.c
@@ -282,7 +282,7 @@ main(int argc, char **argv)
   mrb_value ARGV;
   mrb_value v;
 
-  if (!MRB_OPEN_SUCCESS(mrb)) {
+  if (MRB_OPEN_FAILURE(mrb)) {
     mrb_print_error(mrb);  /* handles NULL */
     mrb_close(mrb);        /* handles NULL */
     return EXIT_FAILURE;
diff --git a/mrbgems/mruby-test/driver.c b/mrbgems/mruby-test/driver.c
index 7caecd54e..fb7f10cf8 100644
--- a/mrbgems/mruby-test/driver.c
+++ b/mrbgems/mruby-test/driver.c
@@ -290,7 +290,7 @@ main(int argc, char **argv)
 
   /* new interpreter instance */
   mrb = mrb_open();
-  if (!MRB_OPEN_SUCCESS(mrb)) {
+  if (MRB_OPEN_FAILURE(mrb)) {
     mrb_print_error(mrb);  /* handles NULL */
     mrb_close(mrb);        /* handles NULL */
     return EXIT_FAILURE;