diff --git a/src/common/mempool.c b/src/common/mempool.c
index 173c6034da..2b1775c1ba 100644
--- a/src/common/mempool.c
+++ b/src/common/mempool.c
@@ -385,11 +385,11 @@ mp_pool_clean(mp_pool_t *pool, int n)
 {
   mp_chunk_t *chunk, **first_to_free;
   if (n < 0) {
+    /* As said in the documentation, "negative n" means "leave an additional
+     * -n chunks". So replace n with a positive number. */
     n = pool->min_empty_chunks + (-n);
     if (n < pool->n_empty_chunks)
       pool->min_empty_chunks = n;
-    /* XXX020 don't we want some sort of return here, given the
-     * assert that follows? -RD */
   }
   ASSERT(n>=0);
 
diff --git a/src/or/config.c b/src/or/config.c
index 0e3cffae82..51610e777d 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -3119,9 +3119,7 @@ options_init_from_torrc(int argc, char **argv)
 
   if (argc > 1 && (!strcmp(argv[1],"--version"))) {
     char vbuf[128];
-    // XXX020 below, tor_svn_revision will always be defined, right?
-    // So we can take out that check? Also in router.c. -RD
-    if (tor_svn_revision != NULL && strlen(tor_svn_revision)) {
+    if (strlen(tor_svn_revision)) {
       tor_snprintf(vbuf, sizeof(vbuf), " (r%s)", tor_svn_revision);
     } else {
       vbuf[0] = 0;
diff --git a/src/or/dns.c b/src/or/dns.c
index 7bd8c7a884..7cf6f9fad4 100644
--- a/src/or/dns.c
+++ b/src/or/dns.c
@@ -562,6 +562,9 @@ dns_resolve(edge_connection_t *exitconn)
       if (!exitconn->_base.marked_for_close) {
         connection_free(TO_CONN(exitconn));
         //XXX020 ... and we just leak exitconn otherwise? -RD
+        // If it's marked for close, it's on closeable_connection_lst in
+        // main.c.  If it's on the closeable list, it will get freed from
+        // main.c. -NM
       }
       break;
     default:
diff --git a/src/or/router.c b/src/or/router.c
index f7418ab00e..50ab1b416c 100644
--- a/src/or/router.c
+++ b/src/or/router.c
@@ -1249,8 +1249,7 @@ void
 get_platform_str(char *platform, size_t len)
 {
   char svn_version_buf[128];
-  if (!strcmpend(VERSION, "-dev") &&
-      tor_svn_revision != NULL && strlen(tor_svn_revision)) {
+  if (!strcmpend(VERSION, "-dev") && strlen(tor_svn_revision)) {
     tor_snprintf(svn_version_buf, sizeof(svn_version_buf), " (r%s)",
                  tor_svn_revision);
   } else {
diff --git a/src/or/routerlist.c b/src/or/routerlist.c
index cbce80be57..bda3a3b50a 100644
--- a/src/or/routerlist.c
+++ b/src/or/routerlist.c
@@ -4856,8 +4856,8 @@ routerinfo_incompatible_with_extrainfo(routerinfo_t *ri, extrainfo_t *ei)
   if (ei->bad_sig)
     return 1;
 
-  /* XXX020 below we should explain why this is strcmp and not strcasecmp,
-   * since it differs from how we usually compare nicknames. -RD */
+  /* The nickname must match exactly to have been generated at the same time
+   * by the same rotuer.  */
   if (strcmp(ri->nickname, ei->nickname) ||
       memcmp(ri->cache_info.identity_digest, ei->cache_info.identity_digest,
              DIGEST_LEN))
diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index 2d363030de..6993158175 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -2142,8 +2142,6 @@ tokenize_string(const char *start, const char *end, smartlist_t *out,
   for (i = 0; table[i].t; ++i) {
     if (counts[table[i].v] < table[i].min_cnt) {
       log_warn(LD_DIR, "Parse error: missing %s element.", table[i].t);
-      tor_assert(0); /* XXX020 is this assert a remote crash waiting to
-                      * happen? -RD */
       return -1;
     }
     if (counts[table[i].v] > table[i].max_cnt) {