diff --git a/gen_newgrf_revisions.py b/gen_newgrf_revisions.py
new file mode 100755
index 0000000000..f53e602110
--- /dev/null
+++ b/gen_newgrf_revisions.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+
+from urllib.request import urlopen
+
+verstr = urlopen("http://finger.openttd.org/tags.txt").read()
+verstr = verstr.decode('utf-8')
+verdata = verstr.strip().split()
+
+releases = []
+f = open("src/newgrf_revisions.cpp", "w")
+f.write('#include "stdafx.h"\n\n')
+f.write('#include <map>\n')
+
+f.write('const std::map<std::string, uint32> OPENTTD_NEWGRF_VERSIONS = {\n')
+for rev, ver in zip(map(int, verdata[0::3]), verdata[2::3]):
+    if ver.startswith('1.1'):
+        break
+    v = ver.split('.')
+    vr = None
+    if '-' in v[2]:
+        v[2], vr = v[2].split('-')
+    v = list(map(int, v))
+    release_flag = int(not bool(vr))
+    newgrf_rev = (v[0] << 28 | v[1] << 24 | v[2] << 20 |
+                  release_flag << 19 | (rev & ((1 << 19) - 1)))
+    f.write('    {{"{}", {}}},\n'.format(ver, newgrf_rev))
+
+    if release_flag and v[2] == 0:
+        newgrf_rev = v[0] << 28 | (v[1] + 1) << 24
+        releases.append((rev, newgrf_rev))
+
+f.write('};\n\n')
+
+f.write('const std::map<uint32, uint32> OPENTTD_RELEASE_REVISIONS = {\n')
+for rev, newgrf_rev in releases:
+    f.write('    {{{}, {}}},\n'.format(rev, newgrf_rev))
+f.write('};\n')
diff --git a/source.list b/source.list
index 5cb9f88d58..6d7486ffb4 100644
--- a/source.list
+++ b/source.list
@@ -605,6 +605,7 @@ zoning_cmd.cpp
 # CityMania files
 citymania/base64.h
 citymania/base64.cpp
+newgrf_revisions.hpp
 
 # Save/Load handlers
 saveload/afterload.cpp
diff --git a/src/network/network_client.cpp b/src/network/network_client.cpp
index bf2ad2d0ad..a7bb58b22e 100644
--- a/src/network/network_client.cpp
+++ b/src/network/network_client.cpp
@@ -31,6 +31,7 @@
 #include "network_base.h"
 #include "network_client.h"
 #include "../core/backup_type.hpp"
+#include "../newgrf_revisions.hpp"
 
 #include "table/strings.h"
 
@@ -41,12 +42,9 @@
 /* This file handles all the client-commands */
 
 void SyncCMUser(const char *msg);
-static const std::map<std::string, uint32> OPENTTD_NEWGRF_VERSIONS = {
-	{"1.7.0", 386428096},
-	{"1.7.0-RC1", 385903751},
-	{"1.6.1", 370699225},
-	{"1.6.0", 369650572},
-};
+// extern const std::map<std::string, uint32> OPENTTD_NEWGRF_VERSIONS;
+// extern const std::map<uint32, uint32> OPENTTD_RELEASE_REVISIONS;
+static const uint32 OPENTTD_NEWGRF_REVISION_MASK = (1 << 19) - 1;
 
 /** Read some packets, and when do use that data as initial load filter. */
 struct PacketReader : LoadFilter {
@@ -349,12 +347,19 @@ NetworkRecvStatus ClientNetworkGameSocketHandler::SendJoin()
 		auto r = _network_join_server_revision;
 		p->Send_string(r);
 		auto nr = OPENTTD_NEWGRF_VERSIONS.find(r);
-		int rev;
+		uint32 rev;
 		if (nr != OPENTTD_NEWGRF_VERSIONS.end()) {
 			p->Send_uint32(nr->second);
-		} else if (r[0] == 'r' && r[6] == 0 && (rev = atoi(r + 1)) > 0) {
+		} else if (r[0] == 'r' && r[6] == 0 && (rev = strtoul(r + 1, nullptr, 10)) > 0) {
 			// assume it's nightly
-			p->Send_uint32((rev >= 27840 ? 402653184u : 385875968u) | rev);
+			uint32 max_rev = 0;
+			// find release closest to the nightly
+			for (auto &kv: OPENTTD_RELEASE_REVISIONS) {
+				if (kv.first > max_rev && kv.first <= rev)
+					max_rev = kv.first;
+			}
+			p->Send_uint32(OPENTTD_RELEASE_REVISIONS.at(max_rev) |
+			               (rev & OPENTTD_NEWGRF_REVISION_MASK));
 		} else {
 			p->Send_uint32(_openttd_newgrf_version);
 		}
diff --git a/src/newgrf_revisions.hpp b/src/newgrf_revisions.hpp
new file mode 100644
index 0000000000..8ed08fb88a
--- /dev/null
+++ b/src/newgrf_revisions.hpp
@@ -0,0 +1,77 @@
+#include "stdafx.h"
+
+#include <map>
+const std::map<std::string, uint32> OPENTTD_NEWGRF_VERSIONS = {
+    {"1.7.1", 387476713},
+    {"1.7.1-RC1", 386952411},
+    {"1.7.0", 386428096},
+    {"1.7.0-RC1", 385903751},
+    {"1.6.1", 370699225},
+    {"1.6.1-RC1", 370174925},
+    {"1.6.0", 369650572},
+    {"1.6.0-RC1", 369126272},
+    {"1.5.3", 356019014},
+    {"1.5.3-RC1", 355494698},
+    {"1.5.2", 354970369},
+    {"1.5.2-RC1", 354446044},
+    {"1.5.1", 353921698},
+    {"1.5.1-RC1", 353397388},
+    {"1.5.0", 352873041},
+    {"1.5.0-RC1", 352348732},
+    {"1.5.0-beta2", 352348706},
+    {"1.5.0-beta1", 352348632},
+    {"1.4.4", 340289941},
+    {"1.4.4-RC1", 339765605},
+    {"1.4.3", 339241250},
+    {"1.4.3-RC2", 338716873},
+    {"1.4.3-RC1", 338716843},
+    {"1.4.2", 338192500},
+    {"1.4.2-RC2", 337668191},
+    {"1.4.2-RC1", 337668146},
+    {"1.4.1", 337143811},
+    {"1.4.1-RC2", 336619496},
+    {"1.4.1-RC1", 336619458},
+    {"1.4.0", 336095048},
+    {"1.4.0-RC1", 335570735},
+    {"1.4.0-beta5", 335570697},
+    {"1.4.0-beta4", 335570621},
+    {"1.4.0-beta3", 335570593},
+    {"1.4.0-beta2", 335570551},
+    {"1.4.0-beta1", 335570498},
+    {"1.3.3", 322463256},
+    {"1.3.3-RC2", 321938928},
+    {"1.3.3-RC1", 321938866},
+    {"1.3.2", 321414176},
+    {"1.3.2-RC2", 320889859},
+    {"1.3.2-RC1", 320889786},
+    {"1.3.1", 320365278},
+    {"1.3.1-RC1", 319840929},
+    {"1.3.0", 319316527},
+    {"1.3.0-RC3", 318792210},
+    {"1.3.0-RC2", 318792173},
+    {"1.3.0-RC1", 318792136},
+    {"1.3.0-beta2", 318792083},
+    {"1.3.0-beta1", 318791955},
+    {"1.2.3", 305684561},
+    {"1.2.3-RC1", 305160229},
+    {"1.2.2", 304635804},
+    {"1.2.2-RC1", 304111495},
+    {"1.2.1", 303587058},
+    {"1.2.1-RC1", 303062723},
+    {"1.2.0", 302538294},
+    {"1.2.0-RC4", 302013972},
+    {"1.2.0-RC3", 302013934},
+    {"1.2.0-RC2", 302013903},
+    {"1.2.0-RC1", 302013859},
+    {"1.2.0-beta4", 302013767},
+    {"1.2.0-beta3", 302013721},
+};
+
+const std::map<uint32, uint32> OPENTTD_RELEASE_REVISIONS = {
+    {27840, 402653184},
+    {27532, 385875968},
+    {27217, 369098752},
+    {26440, 352321536},
+    {25135, 335544320},
+    {24118, 318767104},
+};