diff --git a/ares/ares_dns.h b/ares/ares_dns.h
index a7ae5be17..2187da6e3 100644
--- a/ares/ares_dns.h
+++ b/ares/ares_dns.h
@@ -54,19 +54,19 @@
 #define DNS_HEADER_ARCOUNT(h)           DNS__16BIT((h) + 10)
 
 /* Macros for constructing a DNS header */
-#define DNS_HEADER_SET_QID(h, v)        DNS__SET16BIT(h, v)
-#define DNS_HEADER_SET_QR(h, v)         ((h)[2] |= (((v) & 0x1) << 7))
-#define DNS_HEADER_SET_OPCODE(h, v)     ((h)[2] |= (((v) & 0xf) << 3))
-#define DNS_HEADER_SET_AA(h, v)         ((h)[2] |= (((v) & 0x1) << 2))
-#define DNS_HEADER_SET_TC(h, v)         ((h)[2] |= (((v) & 0x1) << 1))
-#define DNS_HEADER_SET_RD(h, v)         ((h)[2] |= (((v) & 0x1)))
-#define DNS_HEADER_SET_RA(h, v)         ((h)[3] |= (((v) & 0x1) << 7))
-#define DNS_HEADER_SET_Z(h, v)          ((h)[3] |= (((v) & 0x7) << 4))
-#define DNS_HEADER_SET_RCODE(h, v)      ((h)[3] |= (((v) & 0xf)))
-#define DNS_HEADER_SET_QDCOUNT(h, v)    DNS__SET16BIT((h) + 4, v)
-#define DNS_HEADER_SET_ANCOUNT(h, v)    DNS__SET16BIT((h) + 6, v)
-#define DNS_HEADER_SET_NSCOUNT(h, v)    DNS__SET16BIT((h) + 8, v)
-#define DNS_HEADER_SET_ARCOUNT(h, v)    DNS__SET16BIT((h) + 10, v)
+#define DNS_HEADER_SET_QID(h, v)      DNS__SET16BIT(h, v)
+#define DNS_HEADER_SET_QR(h, v)       ((h)[2] |= (unsigned char)(((v) & 0x1) << 7))
+#define DNS_HEADER_SET_OPCODE(h, v)   ((h)[2] |= (unsigned char)(((v) & 0xf) << 3))
+#define DNS_HEADER_SET_AA(h, v)       ((h)[2] |= (unsigned char)(((v) & 0x1) << 2))
+#define DNS_HEADER_SET_TC(h, v)       ((h)[2] |= (unsigned char)(((v) & 0x1) << 1))
+#define DNS_HEADER_SET_RD(h, v)       ((h)[2] |= (unsigned char)((v) & 0x1))
+#define DNS_HEADER_SET_RA(h, v)       ((h)[3] |= (unsigned char)(((v) & 0x1) << 7))
+#define DNS_HEADER_SET_Z(h, v)        ((h)[3] |= (unsigned char)(((v) & 0x7) << 4))
+#define DNS_HEADER_SET_RCODE(h, v)    ((h)[3] |= (unsigned char)((v) & 0xf))
+#define DNS_HEADER_SET_QDCOUNT(h, v)  DNS__SET16BIT((h) + 4, v)
+#define DNS_HEADER_SET_ANCOUNT(h, v)  DNS__SET16BIT((h) + 6, v)
+#define DNS_HEADER_SET_NSCOUNT(h, v)  DNS__SET16BIT((h) + 8, v)
+#define DNS_HEADER_SET_ARCOUNT(h, v)  DNS__SET16BIT((h) + 10, v)
 
 /* Macros for parsing the fixed part of a DNS question */
 #define DNS_QUESTION_TYPE(q)            DNS__16BIT(q)