diff --git a/src/grib_accessor_class_data_complex_packing.c b/src/grib_accessor_class_data_complex_packing.c
index 97c9c4a98..0721c2b52 100644
--- a/src/grib_accessor_class_data_complex_packing.c
+++ b/src/grib_accessor_class_data_complex_packing.c
@@ -294,7 +294,8 @@ static int unpack_double(grib_accessor* a, double* val, size_t *len)
             != GRIB_SUCCESS)
         return ret;
 
-    if((ret = grib_get_long_internal(gh,self->ieee_floats,&ieee_floats)) != GRIB_SUCCESS)
+    /* ECC-774: don't use grib_get_long_internal */
+    if((ret = grib_get_long(gh,self->ieee_floats,&ieee_floats)) != GRIB_SUCCESS)
         return ret;
 
     if((ret = grib_get_double_internal(gh,self->laplacianOperator,&laplacianOperator))
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 6d9874d23..32523ec6b 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -62,6 +62,7 @@ list( APPEND tests_no_data_reqd
 # These tests do require data downloads
 list( APPEND tests_data_reqd
     grib_double_cmp
+    change_packing
     bufr_dump_data
     bufr_dump_decode_filter
     bufr_dump_encode_filter
diff --git a/tests/change_packing.sh b/tests/change_packing.sh
index 94b18c18e..4624ca003 100755
--- a/tests/change_packing.sh
+++ b/tests/change_packing.sh
@@ -11,48 +11,64 @@ grib1=${data_dir}/reduced_latlon_surface_constant.grib1
 grib2=${data_dir}/reduced_latlon_surface_constant.grib2
 
 packing1="
-	grid_ieee
-	grid_simple
-	grid_simple_matrix"
+    grid_ieee
+    grid_simple
+    grid_simple_matrix"
 
 packing2="
-	grid_ieee
-	grid_jpeg
-	grid_simple
-	grid_simple_log_preprocessing
-	grid_simple_matrix"
+    grid_ieee
+    grid_jpeg
+    grid_simple
+    grid_simple_matrix"
+#TODO: grid_simple_log_preprocessing
 
-temp=temp.grib_
+temp=temp.change_packing.grib
 rm -f $temp
 
 # --- test changing the packing
 # arg 1    : input grib file
 # arg 2-n  : packing types to test
 function test_packing() {
-	grib=$1
+    grib=$1
 
-	if [ ! -f $grib ]; then
-		echo "Input data missing"
-		exit 1
-	fi
+    if [ ! -f $grib ]; then
+        echo "Input data missing"
+        exit 1
+    fi
 
-	shift
-	while [ $# -gt 0 ]; do
-		packing=$1
+    shift
+    while [ $# -gt 0 ]; do
+        packing=$1
 
-		${tools_dir}/grib_set -r -s packingType=$packing $grib $temp
-		result=`${tools_dir}/grib_get -p packingType $temp`
-		
-		if [ "$result" != "$packing" ]; then
-			echo "Setting packing did not go right"
-			exit 1
-		fi
+        ${tools_dir}/grib_set -r -s packingType=$packing $grib $temp
+        result=`${tools_dir}/grib_get -p packingType $temp`
+        
+        if [ "$result" != "$packing" ]; then
+            echo "Setting packing did not go right"
+            exit 1
+        fi
 
-		shift
-	done
+        shift
+    done
 
-	rm -f $temp
+    rm -f $temp
 }
 
+# ECC-774
+# ------------
+input=${data_dir}/spherical_model_level.grib2
+output=`${tools_dir}/grib_set -r -s packingType=spectral_simple $input $temp 2>&1`
+# Check no error was posted i.e. output string is empty
+[ -z "$output" ]
+res1=`${tools_dir}/grib_get '-F%.1f' -p avg,enorm $input`
+res2=`${tools_dir}/grib_get '-F%.1f' -p avg,enorm $temp`
+[ "$res1" = "$res2" ]
+rm -f $temp
+
+
+# Change grib packing test
+# -------------------------
 test_packing $grib1 $packing1
 test_packing $grib2 $packing2
+
+rm -f $temp