diff --git a/src/seeder/dns.h b/src/seeder/dns.h
--- a/src/seeder/dns.h
+++ b/src/seeder/dns.h
@@ -8,6 +8,11 @@
 #include <cstddef>
 #include <cstdint>
 
+static const int MAX_QUERY_NAME_LENGTH = 255;
+// Max size of the null-terminated buffer parse_name() writes to.
+static constexpr int MAX_QUERY_NAME_BUFFER_LENGTH = MAX_QUERY_NAME_LENGTH + 1;
+static const size_t MAX_LABEL_LENGTH = 63;
+
 struct addr_t {
     int v;
     union {
@@ -30,8 +35,8 @@
 };
 
 //  0: ok
-// -1: premature end of input, forward reference, component > 63 char, invalid
-// character
+// -1: premature end of input, forward reference, label > MAX_LABEL_LENGTH,
+//     invalid character
 // -2: insufficient space in output
 int parse_name(const uint8_t **inpos, const uint8_t *inend,
                const uint8_t *inbuf, char *buf, size_t bufsize);
diff --git a/src/seeder/dns.cpp b/src/seeder/dns.cpp
--- a/src/seeder/dns.cpp
+++ b/src/seeder/dns.cpp
@@ -74,16 +74,16 @@
             return -1;
         }
         // read length of next component
-        int octet = *((*inpos)++);
+        unsigned int octet = *((*inpos)++);
         if (octet == 0) {
             buf[bufused] = 0;
             return 0;
         }
         // add dot in output
         if (!init) {
-            // The maximum size of a query name is 255. The buffer must have
-            // room for at least the '.' and a valid non-'.' character
-            if (bufused > 253) {
+            // The buffer must have room for at least the '.', a valid
+            // non-'.' character, and a null-terminating character.
+            if (bufused > MAX_QUERY_NAME_BUFFER_LENGTH - 3) {
                 return -1;
             }
             if (bufused == bufsize - 1) {
@@ -106,12 +106,12 @@
             return parse_name(&newbuf, (*inpos) - 2, inbuf, buf + bufused,
                               bufsize - bufused);
         }
-        if (octet > 63) {
+        if (octet > MAX_LABEL_LENGTH) {
             return -1;
         }
         // copy label
         while (octet) {
-            if (*inpos == inend || bufused > 254) {
+            if (*inpos == inend || bufused > MAX_QUERY_NAME_LENGTH - 1) {
                 return -1;
             }
             if (bufused == bufsize - 1) {
@@ -128,7 +128,7 @@
 }
 
 //  0: k
-// -1: component > 63 characters
+// -1: label > MAX_LABEL_LENGTH characters
 // -2: insufficent space in output
 // -3: two subsequent dots
 static int write_name(uint8_t **outpos, const uint8_t *outend, const char *name,
@@ -139,18 +139,19 @@
         if (!dot) {
             fin = name + strlen(name);
         }
-        if (fin - name > 63) {
+        unsigned int labelLength = fin - name;
+        if (labelLength > MAX_LABEL_LENGTH) {
             return -1;
         }
         if (fin == name) {
             return -3;
         }
-        if (outend - *outpos < fin - name + 2) {
+        if (outend - *outpos < labelLength + 2) {
             return -2;
         }
-        *((*outpos)++) = fin - name;
-        memcpy(*outpos, name, fin - name);
-        *outpos += fin - name;
+        *((*outpos)++) = labelLength;
+        memcpy(*outpos, name, labelLength);
+        *outpos += labelLength;
         if (!dot) {
             break;
         }
@@ -421,9 +422,10 @@
     {
         const uint8_t *inpos = inbuf + 12;
         const uint8_t *inend = inbuf + insize;
-        char name[256];
+        char name[MAX_QUERY_NAME_BUFFER_LENGTH];
         int offset = inpos - inbuf;
-        int ret = parse_name(&inpos, inend, inbuf, name, 256);
+        int ret = parse_name(&inpos, inend, inbuf, name,
+                             MAX_QUERY_NAME_BUFFER_LENGTH);
         if (ret == -1) {
             responseCode = DNSResponseCode::FORMAT_ERROR;
             goto error;
diff --git a/src/seeder/test/dns_tests.cpp b/src/seeder/test/dns_tests.cpp
--- a/src/seeder/test/dns_tests.cpp
+++ b/src/seeder/test/dns_tests.cpp
@@ -11,11 +11,7 @@
 
 BOOST_AUTO_TEST_SUITE(dns_tests)
 
-static const int MAX_QUERY_NAME_LENGTH = 255;
-// Max size of the null-terminated buffer parse_name() writes to.
-static const int MAX_QUERY_NAME_BUFFER_LENGTH = MAX_QUERY_NAME_LENGTH + 1;
 static const uint8_t END_OF_NAME_FIELD = 0;
-static const size_t MAX_LABEL_LENGTH = 63;
 
 // Builds the name field of the question section of a DNS query
 static std::vector<uint8_t>