diff --git a/tests/bufr_ecc-765.sh b/tests/bufr_ecc-765.sh
index de06c787c..32e6e25ae 100755
--- a/tests/bufr_ecc-765.sh
+++ b/tests/bufr_ecc-765.sh
@@ -19,10 +19,12 @@ tempLog=temp.${label}.log
 tempSupp=temp.${label}.supp
 tempFilt=temp.${label}.filt
 
+set +u
 if test "x$ECCODES_TEST_WITH_VALGRIND" = "x"; then
   echo "Environment variable ECCODES_TEST_WITH_VALGRIND not defined. Test disabled"
   exit 0
 fi
+set -u
 
 # The presence of ECCODES_TEST_WITH_VALGRIND environment variable redefines
 # tools_dir so we reset it to its original
diff --git a/tests/include.ctest.sh.in b/tests/include.ctest.sh.in
index 1984f63b4..8da7bf747 100644
--- a/tests/include.ctest.sh.in
+++ b/tests/include.ctest.sh.in
@@ -55,6 +55,8 @@ samp_dir="@CMAKE_BINARY_DIR@/@ECCODES_SAMPLES_SUFF@"
 ECCODES_SAMPLES_PATH=${samp_dir}
 export ECCODES_SAMPLES_PATH
 
+set -u
+
 # Options
 HAVE_PRODUCT_BUFR=@HAVE_PRODUCT_BUFR@
 HAVE_PRODUCT_GRIB=@HAVE_PRODUCT_GRIB@