diff --git a/NEWS b/NEWS
index 90eb2286e..388f8dd7b 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,5 @@
 ver 0.21.8 (not yet released)
+* fix build failure with GCC 9
 
 ver 0.21.7 (2019/04/03)
 * input
diff --git a/src/net/IPv4Address.hxx b/src/net/IPv4Address.hxx
index 7a39ed016..3af0210c3 100644
--- a/src/net/IPv4Address.hxx
+++ b/src/net/IPv4Address.hxx
@@ -168,7 +168,7 @@ public:
 	}
 
 	constexpr operator SocketAddress() const noexcept {
-		return SocketAddress((const struct sockaddr *)&address,
+		return SocketAddress((const struct sockaddr *)(const void *)&address,
 				     sizeof(address));
 	}
 
diff --git a/src/net/IPv6Address.hxx b/src/net/IPv6Address.hxx
index e9531b3f7..eae9b60c1 100644
--- a/src/net/IPv6Address.hxx
+++ b/src/net/IPv6Address.hxx
@@ -135,7 +135,7 @@ public:
 	}
 
 	constexpr operator SocketAddress() const noexcept {
-		return SocketAddress((const struct sockaddr *)&address,
+		return SocketAddress((const struct sockaddr *)(const void *)&address,
 				     sizeof(address));
 	}