diff --git a/TargetGroup.cc b/TargetGroup.cc
index 175025f31..52c62c92a 100644
--- a/TargetGroup.cc
+++ b/TargetGroup.cc
@@ -628,7 +628,7 @@ std::string NetBlockIPv6Netmask::str() const {
   return result.str();
 }
 
-NetBlock *NetBlockHostname::resolve() const {
+NetBlock *NetBlockHostname::resolve() {
   struct addrinfo *addrs, *addr;
   std::list<struct sockaddr_storage> resolvedaddrs;
   NetBlock *netblock;
diff --git a/TargetGroup.h b/TargetGroup.h
index 098bd8e63..9200bab48 100644
--- a/TargetGroup.h
+++ b/TargetGroup.h
@@ -162,6 +162,11 @@ public:
 
   bool is_resolved_address(const struct sockaddr_storage *ss) const;
 
+  /* For NetBlock subclasses that need to "resolve" themselves into a different
+   * NetBlock subclass, override this method. Otherwise, it's safe to reassign
+   * the return value to the pointer that this method was called through.
+   * On error, return NULL. */
+  virtual NetBlock *resolve() { return this; }
   virtual bool next(struct sockaddr_storage *ss, size_t *sslen) = 0;
   virtual void apply_netmask(int bits) = 0;
   virtual std::string str() const = 0;
@@ -203,7 +208,7 @@ public:
   int af;
   int bits;
 
-  NetBlock *resolve() const;
+  NetBlock *resolve();
 
   bool next(struct sockaddr_storage *ss, size_t *sslen);
   void apply_netmask(int bits);
diff --git a/targets.cc b/targets.cc
index 4a3926d44..0dd9db2a7 100644
--- a/targets.cc
+++ b/targets.cc
@@ -383,16 +383,13 @@ int TargetGroup::get_next_host(struct sockaddr_storage *ss, size_t *sslen) {
      hostname, without doing local DNS resolution (like with a proxy scan), this
      has to be made conditional (and perhaps an error if the netmask doesn't
      limit it to exactly one address). */
-  NetBlockHostname *netblock_hostname;
-  netblock_hostname = dynamic_cast<NetBlockHostname *>(this->netblock);
-  if (netblock_hostname != NULL) {
-    this->netblock = netblock_hostname->resolve();
-    if (this->netblock == NULL) {
-      error("Failed to resolve \"%s\".", netblock_hostname->hostname.c_str());
-      delete netblock_hostname;
-      return -1;
-    }
-    delete netblock_hostname;
+  NetBlock *netblock_resolved = this->netblock->resolve();
+  if (netblock_resolved != NULL) {
+    this->netblock = netblock_resolved;
+  }
+  else {
+    error("Failed to resolve \"%s\".", this->netblock->hostname.c_str());
+    return -1;
   }
 
   if (this->netblock->next(ss, sslen))