diff --git a/source/functions.c b/source/functions.c
index b88564f..edc3bf1 100644
--- a/source/functions.c
+++ b/source/functions.c
@@ -1252,7 +1252,7 @@ static	char	*alias_server_version  (void)
 #define GET_INT_ARG(x, y) {RETURN_IF_EMPTY(y); x = atol(safe_new_next_arg(y, &y));}
 #define GET_FLOAT_ARG(x, y) {RETURN_IF_EMPTY(y); x = atof(safe_new_next_arg(y, &y));}
 #define GET_STR_ARG(x, y) {RETURN_IF_EMPTY(y); x = new_next_arg(y, &y);RETURN_IF_EMPTY(x);}
-#define RETURN_STR(x) return m_strdup((x) ? (x) : EMPTY)
+#define RETURN_STR(x) return m_strdup((x) != NULL ? (x) : EMPTY)
 #define RETURN_MSTR(x) return ((x) ? (x) : EMPTY_STRING);
 #define RETURN_INT(x) return m_strdup(ltoa(x))