diff --git a/netwerk/dns/DNS.cpp b/netwerk/dns/DNS.cpp
index 4b2fe6b06bce..ddf06944a732 100644
--- a/netwerk/dns/DNS.cpp
+++ b/netwerk/dns/DNS.cpp
@@ -198,6 +198,24 @@ bool NetAddr::IsIPAddrAny() const {
 
 NetAddr::NetAddr(const PRNetAddr* prAddr) { PRNetAddrToNetAddr(prAddr, this); }
 
+nsresult NetAddr::InitFromString(const nsACString& aString, uint16_t aPort) {
+  PRNetAddr prAddr{};
+  memset(&prAddr, 0, sizeof(PRNetAddr));
+  if (PR_StringToNetAddr(PromiseFlatCString(aString).get(), &prAddr) !=
+      PR_SUCCESS) {
+    return NS_ERROR_FAILURE;
+  }
+
+  PRNetAddrToNetAddr(&prAddr, this);
+
+  if (this->raw.family == PR_AF_INET) {
+    this->inet.port = PR_htons(aPort);
+  } else if (this->raw.family == PR_AF_INET6) {
+    this->inet6.port = PR_htons(aPort);
+  }
+  return NS_OK;
+}
+
 bool NetAddr::IsIPAddrV4() const { return this->raw.family == AF_INET; }
 
 bool NetAddr::IsIPAddrV4Mapped() const {
diff --git a/netwerk/dns/DNS.h b/netwerk/dns/DNS.h
index e98d80a00d83..3a3c9cc8527d 100644
--- a/netwerk/dns/DNS.h
+++ b/netwerk/dns/DNS.h
@@ -140,6 +140,12 @@ union NetAddr {
   NetAddr() { memset(this, 0, sizeof(NetAddr)); }
   explicit NetAddr(const PRNetAddr* prAddr);
 
+  // Will parse aString into a NetAddr using PR_StringToNetAddr.
+  // Returns an error code if parsing fails.
+  // If aPort is non-0 will set the NetAddr's port to (the network endian
+  // value of) that.
+  nsresult InitFromString(const nsACString& aString, uint16_t aPort = 0);
+
   bool IsIPAddrAny() const;
   bool IsLoopbackAddr() const;
   bool IsLoopBackAddressWithoutIPv6Mapping() const;