diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index d1f0f760a4..a486216d68 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -28,7 +28,7 @@
 
 #define EDNS0_OPT_DO (1<<15)
 
-#define DNS_PACKET_SIZE_START 512
+#define DNS_PACKET_SIZE_START 512u
 assert_cc(DNS_PACKET_SIZE_START > UDP_PACKET_HEADER_SIZE)
 
 typedef struct DnsPacketRewinder {
diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 3abcaf8cf3..5dff272fd9 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -58,13 +58,13 @@ struct DnsPacketHeader {
 /* The various DNS protocols deviate in how large a packet can grow,
    but the TCP transport has a 16bit size field, hence that appears to
    be the absolute maximum. */
-#define DNS_PACKET_SIZE_MAX 0xFFFF
+#define DNS_PACKET_SIZE_MAX 0xFFFFu
 
 /* RFC 1035 say 512 is the maximum, for classic unicast DNS */
-#define DNS_PACKET_UNICAST_SIZE_MAX 512
+#define DNS_PACKET_UNICAST_SIZE_MAX 512u
 
 /* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */
-#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096
+#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096u
 
 struct DnsPacket {
         int n_ref;