diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index abdd549..c344b98 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -19,6 +19,16 @@ jobs:
         extra_flags: [ -g ]
 
         include:
+          - os: ubuntu-24.04
+            compiler: gfortran
+            version:  9
+          - os: ubuntu-24.04
+            compiler: gfortran
+            version:  10
+          - os: ubuntu-24.04
+            compiler: gfortran
+            version:  11
+
           - os: ubuntu-22.04
             compiler: gfortran
             version: 12 # no package available for gfortran 13+
@@ -145,9 +155,9 @@ jobs:
       run: |
         set -x
         sudo apt update
-        # sudo apt list -a 'gfortran-*'
+        #sudo apt list -a 'gfortran-*'
         sudo apt install -y build-essential
-        if [[ ${COMPILER_VERSION} < 15 ]] ; then \
+        if (( ${COMPILER_VERSION} < 15 )) ; then \
           sudo apt install -y gfortran-${COMPILER_VERSION} ; \
         else \
           curl -L https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh -o install-homebrew.sh ; \
diff --git a/src/assert_m.F90 b/src/assert_m.F90
index 5c4ac36..5147318 100644
--- a/src/assert_m.F90
+++ b/src/assert_m.F90
@@ -151,6 +151,9 @@ pure subroutine assert_always(assertion, description, file, line)
         ! workaround a defect observed in LFortran 0.54:
         ! error stop with an allocatable character argument prints garbage
         error stop message//'', QUIET=.false.
+#elif __GNUC__ && __GNUC__ < 12
+        ! old GFortran lacks the QUIET optional arg added in F2018
+        error stop message
 #else
         error stop message, QUIET=.false.
 #endif