diff --git a/objc/blocks_runtime.h b/objc/blocks_runtime.h
index 030c5c1..9f1545f 100644
--- a/objc/blocks_runtime.h
+++ b/objc/blocks_runtime.h
@@ -5,9 +5,9 @@
 /*
  * Blocks Runtime
  */
-
 #include "Availability.h"
 #ifdef __cplusplus
+#include <stdbool.h>
 #define BLOCKS_EXPORT extern "C"
 #else
 #define BLOCKS_EXPORT extern 
@@ -17,10 +17,18 @@ OBJC_PUBLIC BLOCKS_EXPORT void *_Block_copy(const void *);
 OBJC_PUBLIC BLOCKS_EXPORT void _Block_release(const void *);
 OBJC_PUBLIC BLOCKS_EXPORT const char *block_getType_np(const void *b) OBJC_NONPORTABLE;
 #ifdef __OBJC__
+#ifdef __cplusplus
+OBJC_PUBLIC BLOCKS_EXPORT bool _Block_has_signature(id);
+#else
 OBJC_PUBLIC BLOCKS_EXPORT _Bool _Block_has_signature(id);
+#endif
 OBJC_PUBLIC BLOCKS_EXPORT const char * _Block_signature(id);
 #else
+#ifdef __cplusplus
+OBJC_PUBLIC BLOCKS_EXPORT bool _Block_has_signature(void *);
+#else
 OBJC_PUBLIC BLOCKS_EXPORT _Bool _Block_has_signature(void *);
+#endif
 OBJC_PUBLIC BLOCKS_EXPORT const char * _Block_signature(void *);
 #endif