diff --git a/libidn2-2.0.4-std3-ascii-rules.patch b/libidn2-2.0.4-std3-ascii-rules.patch
new file mode 100644
index 0000000..006223e
--- /dev/null
+++ b/libidn2-2.0.4-std3-ascii-rules.patch
@@ -0,0 +1,82 @@
+From 31b11be35dd841dc1a97c45321b22c3376b01031 Mon Sep 17 00:00:00 2001
+From: Tim Rühsen <tim.ruehsen@gmx.de>
+Date: Thu, 8 Feb 2018 12:52:06 +0100
+Subject: [PATCH] Fix STD3 ASCII rules
+
+---
+ lib/idna.c          | 15 ++++++++++++++-
+ lib/lookup.c        |  5 ++++-
+ tests/test-lookup.c |  9 ++++++++-
+ 3 files changed, 26 insertions(+), 3 deletions(-)
+
+diff --git a/lib/idna.c b/lib/idna.c
+index 5434492..c961332 100644
+--- a/lib/idna.c
++++ b/lib/idna.c
+@@ -180,7 +180,20 @@ _idn2_label_test (int what, const uint32_t * label, size_t llen)
+       size_t i;
+       for (i = 0; i < llen; i++)
+ 	if (_idn2_disallowed_p (label[i]))
+-	  return IDN2_DISALLOWED;
++	  {
++	    if ((what & (TEST_TRANSITIONAL | TEST_NONTRANSITIONAL)) &&
++		(what & TEST_ALLOW_STD3_DISALLOWED))
++	    {
++	      IDNAMap map;
++	      get_idna_map (label[i], &map);
++	      if (map_is (&map, TR46_FLG_DISALLOWED_STD3_VALID) ||
++		  map_is (&map, TR46_FLG_DISALLOWED_STD3_MAPPED))
++	      continue;
++
++	    }
++
++	    return IDN2_DISALLOWED;
++	  }
+     }
+ 
+   if (what & TEST_CONTEXTJ)
+diff --git a/lib/lookup.c b/lib/lookup.c
+index 10b004f..9094aeb 100644
+--- a/lib/lookup.c
++++ b/lib/lookup.c
+@@ -89,7 +89,10 @@ label (const uint8_t * src, size_t srclen, uint8_t * dst, size_t * dstlen,
+ 	TEST_DISALLOWED |
+ 	TEST_CONTEXTJ_RULE |
+ 	TEST_CONTEXTO_WITH_RULE |
+-	TEST_UNASSIGNED | TEST_BIDI, p, plen);
++	TEST_UNASSIGNED | TEST_BIDI |
++	((flags & IDN2_NONTRANSITIONAL) ? TEST_NONTRANSITIONAL : 0) |
++	((flags & IDN2_USE_STD3_ASCII_RULES) ? 0 : TEST_ALLOW_STD3_DISALLOWED),
++	p, plen);
+ 
+       if (rc != IDN2_OK)
+ 	{
+diff --git a/tests/test-lookup.c b/tests/test-lookup.c
+index 03d8396..fb23427 100644
+--- a/tests/test-lookup.c
++++ b/tests/test-lookup.c
+@@ -814,13 +814,20 @@ static const struct idna idna[] = {
+   },
+   /* √.com */
+   {"\xe2\x88\x9a.com", "xn--19g.com", IDN2_OK, IDN2_TRANSITIONAL},
+-  /* domains with non-STD3 characters (removed by default when using TR46 transitional/non-trnasitional */
++  /* domains with non-STD3 characters (removed by default when using TR46 transitional/non-transitional */
+   {"_443._tcp.example.com", "_443._tcp.example.com", IDN2_OK, 0},
+   {"_443._tcp.example.com", "_443._tcp.example.com", IDN2_OK, IDN2_TRANSITIONAL},
+   {"_443._tcp.example.com", "_443._tcp.example.com", IDN2_OK, IDN2_NONTRANSITIONAL},
+   {"_443._tcp.example.com", "443.tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_NONTRANSITIONAL},
+   {"_443._tcp.example.com", "443.tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_TRANSITIONAL},
+   {"_443._tcp.example.com", "_443._tcp.example.com", IDN2_OK, IDN2_USE_STD3_ASCII_RULES}, /* flag is ignored when not using TR46 */
++  /* _��� */
++  {"_\xc3\xbc", "xn--_-eha", IDN2_DISALLOWED, 0},
++  {"_\xc3\xbc", "xn--_-eha", IDN2_OK, IDN2_TRANSITIONAL},
++  {"_\xc3\xbc", "xn--_-eha", IDN2_OK, IDN2_NONTRANSITIONAL},
++  {"_\xc3\xbc", "xn--tda", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_NONTRANSITIONAL},
++  {"_\xc3\xbc", "xn--tda", IDN2_OK, IDN2_USE_STD3_ASCII_RULES|IDN2_TRANSITIONAL},
++  {"_\xc3\xbc", "xn--_-eha", IDN2_DISALLOWED, IDN2_USE_STD3_ASCII_RULES}, /* flag is ignored when not using TR46 */
+ };
+ 
+ static int ok = 0, failed = 0;
+--
+libgit2 0.26.0
+
diff --git a/libidn2.spec b/libidn2.spec
index b4d1789..175b442 100644
--- a/libidn2.spec
+++ b/libidn2.spec
@@ -1,13 +1,14 @@
 Summary:          Library to support IDNA2008 internationalized domain names
 Name:             libidn2
 Version:          2.0.4
-Release:          2%{?dist}
+Release:          3%{?dist}
 License:          (GPLv2+ or LGPLv3+) and GPLv3+
 Group:            System Environment/Libraries
 URL:              https://www.gnu.org/software/libidn/#libidn2
 Source0:          https://ftp.gnu.org/gnu/libidn/%{name}-%{version}.tar.gz
 Source1:          https://ftp.gnu.org/gnu/libidn/%{name}-%{version}.tar.gz.sig
 Patch0:           libidn2-2.0.0-rpath.patch
+Patch1:           libidn2-2.0.4-std3-ascii-rules.patch
 BuildRequires:    libunistring-devel
 Requires(post):   /sbin/install-info, /sbin/ldconfig
 Requires(preun):  /sbin/install-info
@@ -33,6 +34,10 @@ developing applications that use libidn2.
 %patch0 -p1 -b .rpath
 touch -c -r configure.rpath configure
 touch -c -r m4/libtool.m4.rpath m4/libtool.m4
+%patch1 -p1 -b .std3-ascii-rules
+touch -c -r lib/idna.c.std3-ascii-rules lib/idna.c
+touch -c -r lib/lookup.c.std3-ascii-rules lib/lookup.c
+touch -c -r tests/test-lookup.c.std3-ascii-rules tests/test-lookup.c
 
 %build
 %configure --disable-static
@@ -86,6 +91,9 @@ fi
 %{_datadir}/gtk-doc/
 
 %changelog
+* Sun Feb 18 2018 Robert Scheck <robert@fedoraproject.org> 2.0.4-3
+- Added upstream patch to fix STD3 ASCII rules (#1543021)
+
 * Wed Feb 07 2018 Fedora Release Engineering <releng@fedoraproject.org> - 2.0.4-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_28_Mass_Rebuild