diff --git a/tests/unit/check_sockutil.c b/tests/unit/check_sockutil.c
index 0c8332a..b7598ef 100644
--- a/tests/unit/check_sockutil.c
+++ b/tests/unit/check_sockutil.c
@@ -75,6 +75,7 @@ START_TEST( test_sockaddr_address_string_doesnt_overflow_short_buffer )
 	v4->sin_family = AF_INET;
 	v4->sin_port = htons( 4777 );
 	ck_assert_int_eq( 1, inet_pton( AF_INET, "192.168.0.1", &v4->sin_addr ));
+	memset( &testbuf, 0, 128 );
 
 	result = sockaddr_address_string( &sa, &testbuf[0], 2 );
 	ck_assert( result == NULL );