diff --git a/SOURCES/0002-add-support-for-RFC3021.patch b/SOURCES/0002-add-support-for-RFC3021.patch
new file mode 100644
index 0000000..2db25b4
--- /dev/null
+++ b/SOURCES/0002-add-support-for-RFC3021.patch
@@ -0,0 +1,28 @@
+diff --git a/ipcalc.c b/ipcalc.c
+index f2bc47a..04c9372 100644
+--- a/ipcalc.c
++++ b/ipcalc.c
+@@ -146,7 +146,12 @@ static struct in_addr calc_broadcast(struct in_addr addr, int prefix)
+ 	mask.s_addr = prefix2mask(prefix);
+ 
+ 	memset(&broadcast, 0, sizeof(broadcast));
+-	broadcast.s_addr = (addr.s_addr & mask.s_addr) | ~mask.s_addr;
++
++	/* if prefix is set to 31 return 255.255.255.255 (RFC3021) */
++	if (mask.s_addr ==  htonl(0xFFFFFFFE))
++		broadcast.s_addr = htonl(0xFFFFFFFF);
++	else
++		broadcast.s_addr = (addr.s_addr & mask.s_addr) | ~mask.s_addr;
+ 	return broadcast;
+ }
+ 
+diff --git a/tests/192.168.1.5-31 b/tests/192.168.1.5-31
+index fee8227..b720b56 100644
+--- a/tests/192.168.1.5-31
++++ b/tests/192.168.1.5-31
+@@ -1,4 +1,4 @@
+ NETMASK=255.255.255.254
+ PREFIX=31
+-BROADCAST=192.168.1.5
++BROADCAST=255.255.255.255
+ NETWORK=192.168.1.4
diff --git a/SPECS/ipcalc.spec b/SPECS/ipcalc.spec
index 4213d72..f5d12c0 100644
--- a/SPECS/ipcalc.spec
+++ b/SPECS/ipcalc.spec
@@ -1,6 +1,6 @@
 Name: ipcalc
 Version: 0.2.4
-Release: 3%{?dist}
+Release: 4%{?dist}
 Summary: IP network address calculator
 
 # This is an updated version of ipcalc originally found
@@ -20,6 +20,7 @@ Conflicts: initscripts < 9.63
 Obsoletes:  ipcalculator < 0.41-20
 
 Patch1: 0001-fix-segfault-in-env-without-libmaxmind.so.patch
+Patch2: 0002-add-support-for-RFC3021.patch
 
 %description
 ipcalc provides a simple way to calculate IP information for a host
@@ -52,6 +53,9 @@ make check
 %{_mandir}/man1/ipcalc.1*
 
 %changelog
+* Thu Oct 10 2019 Martin Osvald <mosvald@redhat.com> - 0.2.4-4
+- Add support for RFC3021 (#1638834)
+
 * Fri Aug 03 2018 Martin Sehnoutka <msehnout@redhat.com> - 0.2.4-3
 - Fix segfault in the container environment