diff --git a/src/grib_util.c b/src/grib_util.c
index c5f32a502..de8ba1056 100644
--- a/src/grib_util.c
+++ b/src/grib_util.c
@@ -1851,12 +1851,15 @@ int is_index_file(const char* filename)
     char buf[8]={0,};
     const char* str="GRBIDX";
     int ret=0;
+    size_t size = 0;
 
     fh=fopen(filename,"r");
     if (!fh) return 0;
 
-    fread(buf,1,1,fh);
-    fread(buf,6,1,fh);
+    size=fread(buf,1,1,fh);
+    if (size != 1) return 0;
+    size=fread(buf,6,1,fh);
+    if (size != 1) return 0;
 
     ret=!strcmp(buf,str);
 
diff --git a/tests/index.sh b/tests/index.sh
index cb714669d..4e80bce69 100755
--- a/tests/index.sh
+++ b/tests/index.sh
@@ -13,12 +13,6 @@
 . ./include.sh
 infile=${data_dir}/index.grib
 
-#if [ ! -f ${infile} ]
-#then
-#  echo no data to test
-#  exit 0
-#fi
-
 $EXEC ${test_dir}/index ${infile} > index.out
 
 diff index.out ${data_dir}/index.ok
@@ -32,9 +26,30 @@ rm -f index.out out.gribidx
 #-------------------------------
 # Test grib_index_build
 #-------------------------------
-tempIndex=temp.$$.ix
+tempIndex=temp.$$.idx
+tempOut=temp.$$.out
+tempRef=temp.$$.ref
 ${tools_dir}/grib_index_build -o $tempIndex ${infile} >/dev/null
-${tools_dir}/grib_dump -D ${tempIndex} > /dev/null
+
+# Must remove first two lines and the last (filename specifics)
+${tools_dir}/grib_dump -D ${tempIndex} | sed '1,2d' | sed '$d' > $tempOut
+cat $tempOut
+
+cat > $tempRef <<EOF
+Index keys:
+key name = mars.step
+values = 12, 24, 48, 60
+key name = mars.param
+values = 130.128, 129.128
+key name = mars.levelist
+values = 10, 50, 100, 200, 250, 300, 400, 500, 700, 850, 925, 1000
+key name = mars.number
+values = 1, 2, 3, 4
+Index count = 384
+EOF
+
+diff $tempRef $tempOut
+
 
 ${tools_dir}/grib_index_build -k mars.levtype -o $tempIndex ${data_dir}/tigge_cf_ecmwf.grib2 |\
    grep -q "mars.levtype = { sfc, pl, pv, pt }"
@@ -42,4 +57,4 @@ ${tools_dir}/grib_index_build -k mars.levtype -o $tempIndex ${data_dir}/tigge_cf
 ${tools_dir}/grib_index_build -k mars.levtype:i -o $tempIndex ${data_dir}/tigge_cf_ecmwf.grib2 |\
    grep -q "mars.levtype = { 103, 1, 106, 100, 101, 8, 109, 107 }"
 
-rm -f $tempIndex
+rm -f $tempIndex $tempOut $tempRef