diff -Nru emoslib-4.5.9/debian/changelog emoslib-4.5.9/debian/changelog
--- emoslib-4.5.9/debian/changelog	2020-08-03 19:47:15.000000000 +0000
+++ emoslib-4.5.9/debian/changelog	2021-09-06 19:11:18.000000000 +0000
@@ -1,3 +1,11 @@
+emoslib (2:4.5.9-7) unstable; urgency=medium
+
+  * Change gfortran conditional flags to work with gfortran 11.
+    Closes: #984046
+  * Standards-Version:4.6.0
+
+ -- Alastair McKinstry <mckinstry@debian.org>  Mon, 06 Sep 2021 20:11:18 +0100
+
 emoslib (2:4.5.9-6) unstable; urgency=medium
 
   * Fix needed for gfortran-10 changes. Closes: #966956
diff -Nru emoslib-4.5.9/debian/control emoslib-4.5.9/debian/control
--- emoslib-4.5.9/debian/control	2020-08-03 19:47:15.000000000 +0000
+++ emoslib-4.5.9/debian/control	2021-09-06 19:11:18.000000000 +0000
@@ -14,7 +14,7 @@
  zlib1g-dev,
  libfftw3-dev,
  libnetcdf-dev
-Standards-Version: 4.5.0
+Standards-Version: 4.6.0
 Homepage: https://software.ecmwf.int/wiki/display/EMOS/Emoslib
 Vcs-Browser: https://salsa.debian.org:/science-team/emos
 Vcs-Git: https://salsa.debian.org:/science-team/emos.git
diff -Nru emoslib-4.5.9/debian/rules emoslib-4.5.9/debian/rules
--- emoslib-4.5.9/debian/rules	2020-08-03 19:47:15.000000000 +0000
+++ emoslib-4.5.9/debian/rules	2021-09-06 19:11:18.000000000 +0000
@@ -15,9 +15,8 @@
 
 # gfortran warns of type mismatch on Fortran/C code. Not worth fixing this by redesign
 # (porting to F90) when its being replaced by mir. Just disable the warning
-GF10_FLAGS:=$(if $(filter $(shell readlink /usr/bin/gfortran), gfortran-10), \
-		 -fallow-argument-mismatch, )
-
+GF_FLAGS:=$(if $(filter $(shell readlink /usr/bin/gfortran), gfortran-9), \
+                 , -fallow-invalid-boz -fallow-argument-mismatch )
 DESTDIR:=$(shell pwd)/debian/tmp
 DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 ARCH:=$(shell dpkg --print-architecture)
@@ -35,7 +34,7 @@
 ifneq ($(filter flang,$(FC)),)
 FFLAGS:=$(shell dpkg-buildflags --get FCFLAGS |  sed -e 's/-g //')
 else
-FFLAGS:=$(shell dpkg-buildflags --get FCFLAGS ) $(GF10_FLAGS) 
+FFLAGS:=$(shell dpkg-buildflags --get FCFLAGS ) $(GF_FLAGS) 
 endif
 
 export FCFLAGS=$(FFLAGS)