diff --git a/src/grib_accessor_class_data_ccsds_packing.c b/src/grib_accessor_class_data_ccsds_packing.c
index b952c8e11..c10079085 100644
--- a/src/grib_accessor_class_data_ccsds_packing.c
+++ b/src/grib_accessor_class_data_ccsds_packing.c
@@ -214,7 +214,7 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
     grib_handle* hand = grib_handle_of_accessor(a);
 
     int err = GRIB_SUCCESS, i = 0;
-    size_t buflen = grib_byte_count(a);
+    size_t buflen = 0;
     struct aec_stream strm;
     double bscale      = 0;
     double dscale      = 0;
@@ -260,9 +260,6 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
     if ((err = grib_get_long_internal(hand, self->ccsds_rsi, &ccsds_rsi)) != GRIB_SUCCESS)
         return err;
 
-    bscale = grib_power(binary_scale_factor, 2);
-    dscale = grib_power(-decimal_scale_factor, 10);
-
     /* TODO: This should be called upstream */
     if (*len < n_vals)
         return GRIB_ARRAY_TOO_SMALL;
@@ -275,6 +272,10 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
         return GRIB_SUCCESS;
     }
 
+    bscale = grib_power(binary_scale_factor, 2);
+    dscale = grib_power(-decimal_scale_factor, 10);
+
+    buflen = grib_byte_count(a);
     buf = (unsigned char*)hand->buffer->data;
     buf += grib_byte_offset(a);
 
diff --git a/tests/include.ctest.sh.in b/tests/include.ctest.sh.in
index 2f313212b..2330af454 100644
--- a/tests/include.ctest.sh.in
+++ b/tests/include.ctest.sh.in
@@ -1,6 +1,24 @@
 set -ea
 # For CMake
 
+# Unset any environment variable that could interfere with tests
+unset ECCODES_EXTRA_DEFINITION_PATH
+unset ECCODES_LOG_STREAM
+unset ECCODES_FAIL_IF_LOG_MESSAGE
+unset ECCODES_DEBUG
+unset ECCODES_GRIB_WRITE_ON_FAIL
+unset ECCODES_GRIB_DATA_QUALITY_CHECKS
+unset ECCODES_GRIB_KEEP_MATRIX
+unset ECCODES_GRIB_NO_SPD
+unset ECCODES_GRIB_NO_BIG_GROUP_SPLIT
+unset ECCODES_GRIB_IEEE_PACKING
+unset ECCODES_GRIBEX_MODE_ON
+unset ECCODES_BUFRDC_MODE_ON
+unset ECCODES_BUFR_SET_TO_MISSING_IF_OUT_OF_RANGE
+unset ECCODES_BUFR_MULTI_ELEMENT_CONSTANT_ARRAYS
+unset ECCODES_FILE_POOL_MAX_OPENED_FILES
+unset ECCODES_IO_BUFFER_SIZE
+
 set -x
 echo "Script: $0"