diff --git a/src/handshake.h b/src/handshake.h
index 7136087a..7f597b06 100644
--- a/src/handshake.h
+++ b/src/handshake.h
@@ -164,23 +164,27 @@ struct handshake_state {
 	handshake_event_func_t event_func;
 };
 
-#define handshake_event(_hs, event, ...)	\
-	(__extension__ ({	\
-		bool freed = false;	\
-	\
-		if ((_hs)->event_func && !(_hs)->in_event) {	\
-			(_hs)->in_event = true;	\
-			(_hs)->event_func((_hs), event, (_hs)->user_data,	\
-					##__VA_ARGS__); \
-	\
-			if (!(_hs)->in_event) {	\
-				handshake_state_free((_hs));	\
-				freed = true;	\
-			} else	\
-				(_hs)->in_event = false;	\
-		}	\
-		freed;	\
-	}))
+#define HSID(x) UNIQUE_ID(handshake_, x)
+
+#define handshake_event(_hs, event, ...)				\
+	({								\
+		bool HSID(freed) = false;				\
+		typeof(_hs) HSID(hs) = (_hs);				\
+									\
+		if (HSID(hs)->event_func && !HSID(hs)->in_event) {	\
+			HSID(hs)->in_event = true;			\
+			HSID(hs)->event_func(HSID(hs), (event),		\
+					HSID(hs)->user_data,		\
+					##__VA_ARGS__);			\
+									\
+			if (!HSID(hs)->in_event) {			\
+				handshake_state_free(HSID(hs));		\
+				HSID(freed) = true;			\
+			} else						\
+				HSID(hs)->in_event = false;		\
+		}							\
+		HSID(freed);						\
+	})
 
 void handshake_state_free(struct handshake_state *s);
 
diff --git a/src/util.h b/src/util.h
index b55a7ea7..75c29039 100644
--- a/src/util.h
+++ b/src/util.h
@@ -26,6 +26,10 @@
 #include <stdint.h>
 #include <unistd.h>
 
+#define ___PASTE(a, b) a ## b
+#define __PASTE(a, b) ___PASTE(a, b)
+#define UNIQUE_ID(x, id) __PASTE(__unique_prefix_, __PASTE(x, id))
+
 #define align_len(len, boundary) (((len)+(boundary)-1) & ~((boundary)-1))
 
 #define MAC "%02x:%02x:%02x:%02x:%02x:%02x"