diff --git a/src/grib_accessor_class_latitudes.cc b/src/grib_accessor_class_latitudes.cc
index 90f6601bf..96c529d8e 100644
--- a/src/grib_accessor_class_latitudes.cc
+++ b/src/grib_accessor_class_latitudes.cc
@@ -188,11 +188,11 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
 {
     grib_context* c               = a->context;
     grib_accessor_latitudes* self = (grib_accessor_latitudes*)a;
-    int ret                       = 0;
-    double* v                     = val;
-    double dummyLon = 0, dummyVal = 0;
-    size_t size         = 0;
-    long count          = 0;
+    int ret = 0;
+    double* v = val;
+    double dummyLon = 0;
+    size_t size = 0;
+    long count = 0;
     grib_iterator* iter = NULL;
 
     self->save = 1;
@@ -221,7 +221,8 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
         return GRIB_SUCCESS;
     }
 
-    iter = grib_iterator_new(grib_handle_of_accessor(a), 0, &ret);
+    // Performance: We do not need the values to be decoded
+    iter = grib_iterator_new(grib_handle_of_accessor(a), GRIB_GEOITERATOR_NO_VALUES, &ret);
     if (ret != GRIB_SUCCESS) {
         if (iter)
             grib_iterator_delete(iter);
@@ -229,7 +230,7 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
         return ret;
     }
 
-    while (grib_iterator_next(iter, v++, &dummyLon, &dummyVal)) {}
+    while (grib_iterator_next(iter, v++, &dummyLon, NULL)) {}
     grib_iterator_delete(iter);
 
     *len = size;
@@ -275,13 +276,15 @@ static int get_distinct(grib_accessor* a, double** val, long* len)
     double prev;
     double* v       = NULL;
     double* v1      = NULL;
-    double dummyLon = 0, dummyVal = 0;
+    double dummyLon = 0;
     int ret = 0;
     int i;
     long jScansPositively = 0; /* default: north to south */
     size_t size           = *len;
     grib_context* c       = a->context;
-    grib_iterator* iter   = grib_iterator_new(grib_handle_of_accessor(a), 0, &ret);
+
+    // Performance: We do not need the values to be decoded
+    grib_iterator* iter   = grib_iterator_new(grib_handle_of_accessor(a), GRIB_GEOITERATOR_NO_VALUES, &ret);
     if (ret != GRIB_SUCCESS) {
         if (iter)
             grib_iterator_delete(iter);
@@ -295,7 +298,7 @@ static int get_distinct(grib_accessor* a, double** val, long* len)
     }
     *val = v;
 
-    while (grib_iterator_next(iter, v++, &dummyLon, &dummyVal)) {}
+    while (grib_iterator_next(iter, v++, &dummyLon, NULL)) {}
     grib_iterator_delete(iter);
     v = *val;
 
diff --git a/src/grib_accessor_class_longitudes.cc b/src/grib_accessor_class_longitudes.cc
index 03f08f6be..e12a622ed 100644
--- a/src/grib_accessor_class_longitudes.cc
+++ b/src/grib_accessor_class_longitudes.cc
@@ -165,9 +165,9 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
     grib_accessor_longitudes* self = (grib_accessor_longitudes*)a;
     int ret                        = 0;
     double* v                      = val;
-    double dummyLat = 0, dummyVal = 0;
-    size_t size         = 0;
-    long count          = 0;
+    double dummyLat = 0;
+    size_t size = 0;
+    long count = 0;
     grib_iterator* iter = NULL;
 
     self->save = 1;
@@ -197,7 +197,8 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
         return GRIB_SUCCESS;
     }
 
-    iter = grib_iterator_new(grib_handle_of_accessor(a), 0, &ret);
+    // Performance: We do not need the values to be decoded
+    iter = grib_iterator_new(grib_handle_of_accessor(a), GRIB_GEOITERATOR_NO_VALUES, &ret);
     if (ret != GRIB_SUCCESS) {
         if (iter)
             grib_iterator_delete(iter);
@@ -205,7 +206,7 @@ static int unpack_double(grib_accessor* a, double* val, size_t* len)
         return ret;
     }
 
-    while (grib_iterator_next(iter, &dummyLat, v++, &dummyVal)) {}
+    while (grib_iterator_next(iter, &dummyLat, v++, NULL)) {}
     grib_iterator_delete(iter);
 
     *len = size;
@@ -250,12 +251,14 @@ static int get_distinct(grib_accessor* a, double** val, long* len)
     double prev;
     double* v       = NULL;
     double* v1      = NULL;
-    double dummyLat = 0, dummyVal = 0;
+    double dummyLat = 0;
     int ret = 0;
     int i;
     size_t size         = *len;
     grib_context* c     = a->context;
-    grib_iterator* iter = grib_iterator_new(grib_handle_of_accessor(a), 0, &ret);
+
+    // Performance: We do not need the values to be decoded
+    grib_iterator* iter = grib_iterator_new(grib_handle_of_accessor(a), GRIB_GEOITERATOR_NO_VALUES, &ret);
     if (ret != GRIB_SUCCESS) {
         if (iter)
             grib_iterator_delete(iter);
@@ -269,7 +272,7 @@ static int get_distinct(grib_accessor* a, double** val, long* len)
     }
     *val = v;
 
-    while (grib_iterator_next(iter, &dummyLat, v++, &dummyVal)) {}
+    while (grib_iterator_next(iter, &dummyLat, v++, NULL)) {}
     grib_iterator_delete(iter);
     v = *val;
 
diff --git a/src/grib_iterator_class_gen.cc b/src/grib_iterator_class_gen.cc
index ee9942045..acdf425a8 100644
--- a/src/grib_iterator_class_gen.cc
+++ b/src/grib_iterator_class_gen.cc
@@ -184,6 +184,7 @@ static int init(grib_iterator* iter, grib_handle* h, grib_arguments* args)
     self->missingValue = grib_arguments_get_name(h, args, self->carg++);
     s_rawData          = grib_arguments_get_name(h, args, self->carg++);
 
+    iter->data = NULL;
     iter->h    = h; /* We may not need to keep them */
     iter->args = args;
     if ((err = grib_get_size(h, s_rawData, &dli)) != GRIB_SUCCESS)
@@ -203,7 +204,9 @@ static int init(grib_iterator* iter, grib_handle* h, grib_arguments* args)
         return GRIB_WRONG_GRID;
     }
 
-    if (iter->flags == 0) {
+    if ((iter->flags & GRIB_GEOITERATOR_NO_VALUES) == 0) {
+        // When the NO_VALUES flag is unset, decode the values and store them in the iterator.
+        // By default (and legacy) flags==0, so we decode
         iter->data = (double*)grib_context_malloc(h->context, (iter->nv) * sizeof(double));
 
         if ((err = grib_get_double_array_internal(h, s_rawData, iter->data, &(iter->nv))))
diff --git a/tests/grib_geo_iter.cc b/tests/grib_geo_iter.cc
index fb8482632..28b7603fe 100644
--- a/tests/grib_geo_iter.cc
+++ b/tests/grib_geo_iter.cc
@@ -13,29 +13,60 @@
 
 #include "grib_api_internal.h"
 
+typedef enum IterMode
+{
+    WITH_VALUES,
+    NO_VALUES
+} IterMode;
+
 int main(int argc, char** argv)
 {
     int err  = 0;
-    double lat, lon, value;
-    int n                        = 0;
-    const int numberOfDataPoints = 13280;
-    const char* sample_filename  = "gg_sfc_grib2";
-    grib_handle* h               = NULL;
-    grib_iterator* iter          = NULL;
+    double lat = 0, lon = 0, value = 0;
+    long n = 0, numberOfDataPoints = 0;
+    char* filename = NULL;
+    FILE* fin = NULL;
+    grib_handle* h = NULL;
+    grib_iterator* iter = NULL;
+    char* option = NULL;
+    IterMode mode = WITH_VALUES;
+    int flags = 0;
+    double* pValue = NULL;
+    bool verbose = false;
 
-    h = grib_handle_new_from_samples(0, sample_filename);
+    Assert(argc == 3);
+    option = argv[1];
+    filename = argv[2];
+    if (strcmp(option, "-n")==0) {
+        mode = NO_VALUES;
+    }
+
+    fin = fopen(filename, "rb");
+    Assert(fin);
+    h = grib_handle_new_from_file(0, fin, &err);
+    Assert(!err);
     Assert(h);
 
-    iter = grib_iterator_new(h, 0, &err);
+    GRIB_CHECK(grib_get_long(h,"numberOfDataPoints", &numberOfDataPoints),0);
+
+    flags = (mode == NO_VALUES) ? GRIB_GEOITERATOR_NO_VALUES : 0;
+    iter = grib_iterator_new(h, flags, &err);
     Assert(!err);
     Assert(iter);
 
     Assert(grib_iterator_has_next(iter));
     n = 0;
 
-    while (grib_iterator_next(iter, &lat, &lon, &value)) {
-        if (n < numberOfDataPoints - 1)
+    pValue = (mode == NO_VALUES) ? NULL : &value;
+    while (grib_iterator_next(iter, &lat, &lon, pValue)) {
+        if (n < numberOfDataPoints - 1) {
             Assert(grib_iterator_has_next(iter));
+        }
+        if (verbose) {
+            printf("%9.3f %9.3f ",lat, lon);
+            if (pValue) printf(" %.10e\n", *pValue);
+            else printf("\n");
+        }
         n++;
     }
     Assert(n == numberOfDataPoints);
diff --git a/tests/grib_geo_iter.sh b/tests/grib_geo_iter.sh
index 4c3af0c86..631d2485b 100755
--- a/tests/grib_geo_iter.sh
+++ b/tests/grib_geo_iter.sh
@@ -12,4 +12,33 @@
 
 label="grib_geo_iter_test"
 
-$EXEC ${test_dir}/grib_geo_iter
+infiles="
+    $ECCODES_SAMPLES_PATH/gg_sfc_grib2.tmpl
+    $ECCODES_SAMPLES_PATH/reduced_ll_sfc_grib1.tmpl
+    $ECCODES_SAMPLES_PATH/regular_gg_ml_grib2.tmpl
+    $ECCODES_SAMPLES_PATH/polar_stereographic_pl_grib2.tmpl
+    $data_dir/regular_latlon_surface.grib1
+    $data_dir/mercator.grib2
+"
+
+# Run the iterator in two modes:
+#  -v  decodes the values
+#  -n  does not decode the values
+infile=$ECCODES_SAMPLES_PATH/gg_sfc_grib2.tmpl
+for infile in $infiles; do
+    $EXEC ${test_dir}/grib_geo_iter -v $infile
+    $EXEC ${test_dir}/grib_geo_iter -n $infile
+done
+
+# Test a case where decoding is not possible but the iterator would work
+if [ $HAVE_JPEG -eq 0 ]; then
+    # No JPEG, so cannot decode the field but the iterator doesn't need to
+    infile=$data_dir/jpeg.grib2
+    set +e
+    ${tools_dir}/grib_get -p min,max $infile
+    status=$?
+    set -e
+    [ $status -ne 0 ]  # Make sure it fails to decode
+
+    $EXEC ${test_dir}/grib_geo_iter -n $infile
+fi