diff -Nru mpich-3.4.1/debian/changelog mpich-3.4.1/debian/changelog
--- mpich-3.4.1/debian/changelog	2021-08-10 12:03:27.000000000 -0400
+++ mpich-3.4.1/debian/changelog	2021-08-31 21:12:19.000000000 -0400
@@ -1,3 +1,10 @@
+mpich (3.4.1-5ubuntu1) impish; urgency=medium
+
+  * d/rules: Make GF10_FLAGS become GF11_FLAGS, to account for
+    GCC/GFortran 11. (LP: #1942265)
+
+ -- Sergio Durigan Junior <sergio.durigan@canonical.com>  Tue, 31 Aug 2021 21:12:19 -0400
+
 mpich (3.4.1-5) unstable; urgency=medium
 
   * Team upload.
diff -Nru mpich-3.4.1/debian/control mpich-3.4.1/debian/control
--- mpich-3.4.1/debian/control	2021-08-10 12:03:27.000000000 -0400
+++ mpich-3.4.1/debian/control	2021-08-31 21:12:19.000000000 -0400
@@ -1,5 +1,6 @@
 Source: mpich
-Maintainer: Debian Science Maintainers <debian-science-maintainers@lists.alioth.debian.org>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Debian Science Maintainers <debian-science-maintainers@lists.alioth.debian.org>
 Uploaders: Torquil Macdonald Sørensen <torquil@gmail.com>,
            "Adam C. Powell, IV" <hazelsct@debian.org>,
            Alastair McKinstry <mckinstry@debian.org>
diff -Nru mpich-3.4.1/debian/rules mpich-3.4.1/debian/rules
--- mpich-3.4.1/debian/rules	2021-08-10 12:03:27.000000000 -0400
+++ mpich-3.4.1/debian/rules	2021-08-31 21:07:11.000000000 -0400
@@ -4,15 +4,15 @@
 
 DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
-GF10_FLAGS:=$(if $(filter $(shell readlink /usr/bin/gfortran), gfortran-10), \
+GF11_FLAGS:=$(if $(filter $(shell readlink /usr/bin/gfortran), gfortran-11), \
                  -fallow-invalid-boz -fallow-argument-mismatch, )
 
 export MPICHLIB_CPPFLAGS=$(shell dpkg-buildflags --get CPPFLAGS)
 export MPICHLIB_CFLAGS=$(shell dpkg-buildflags --get CFLAGS)
 export MPICHLIB_CXXFLAGS=$(shell dpkg-buildflags --get CXXFLAGS)
-export MPICHLIB_FFLAGS=$(shell dpkg-buildflags --get FFLAGS) $(GF10_FLAGS)
-export MPICHLIB_FCFLAGS=$(shell dpkg-buildflags --get FFLAGS) -cpp $(GF10_FLAGS)
-export FFLAGS=$(shell dpkg-buildflags --get FFLAGS |  sed -e 's/-g //') $(GF10_FLAGS)
+export MPICHLIB_FFLAGS=$(shell dpkg-buildflags --get FFLAGS) $(GF11_FLAGS)
+export MPICHLIB_FCFLAGS=$(shell dpkg-buildflags --get FFLAGS) -cpp $(GF11_FLAGS)
+export FFLAGS=$(shell dpkg-buildflags --get FFLAGS |  sed -e 's/-g //') $(GF11_FLAGS)
 export F77=f77
 export TZ=UTC+0