diff --git a/definitions/boot.def b/definitions/boot.def
index dc6f71b94..5cbac2743 100644
--- a/definitions/boot.def
+++ b/definitions/boot.def
@@ -11,8 +11,6 @@ constant definitionFilesVersion="2.0.0.0" : hidden;
 constant internalVersion=30 : hidden;
 meta checkInternalVersion check_internal_version(internalVersion) : hidden;
 
-meta isMessageValid message_is_valid() : hidden;
-
 # ECC-806: Local concepts precedence order
 preferLocalConceptsEnvVar = getenv("ECCODES_GRIB_PREFER_LOCAL_CONCEPTS","0") : hidden;
 transient preferLocalConcepts = preferLocalConceptsEnvVar : hidden;
@@ -126,3 +124,5 @@ if(kindOfProduct == `WRAP`){
  constant WRAPstr="WRAP";
  alias ls.identifier=WRAPstr;
 }
+
+meta isMessageValid message_is_valid(kindOfProduct) : hidden;
diff --git a/src/accessor/grib_accessor_class_message_is_valid.cc b/src/accessor/grib_accessor_class_message_is_valid.cc
index 522a0e360..a467c88f0 100644
--- a/src/accessor/grib_accessor_class_message_is_valid.cc
+++ b/src/accessor/grib_accessor_class_message_is_valid.cc
@@ -13,9 +13,13 @@
 grib_accessor_message_is_valid_t _grib_accessor_message_is_valid{};
 grib_accessor* grib_accessor_message_is_valid = &_grib_accessor_message_is_valid;
 
-void grib_accessor_message_is_valid_t::init(const long l, grib_arguments* c)
+void grib_accessor_message_is_valid_t::init(const long l, grib_arguments* arg)
 {
-    grib_accessor_long_t::init(l, c);
+    grib_accessor_long_t::init(l, arg);
+
+    grib_handle* h = grib_handle_of_accessor(this);
+    product_ = arg->get_name(h, 0);
+
     flags_ |= GRIB_ACCESSOR_FLAG_READ_ONLY;
     length_ = 0;
 }
@@ -96,10 +100,16 @@ int grib_accessor_message_is_valid_t::unpack_long(long* val, size_t* len)
 {
     int ret = 0;
     grib_handle* h = grib_handle_of_accessor(this);
+
     *len = 1;
     *val = 1; // Assume message is valid
 
-    if (h->product_kind != PRODUCT_GRIB) {
+    char product[32] = {0,};
+    size_t size = sizeof(product) / sizeof(*product);
+    ret = grib_get_string(h, product_, product, &size);
+    if (ret) return ret;
+
+    if (!STR_EQUAL(product, "GRIB")) {
         grib_context_log(h->context, GRIB_LOG_ERROR, "Validity checks only implemented for GRIB messages");
         *val = 0;
         return GRIB_NOT_IMPLEMENTED;
diff --git a/src/accessor/grib_accessor_class_message_is_valid.h b/src/accessor/grib_accessor_class_message_is_valid.h
index 9ebd54a27..5d380362c 100644
--- a/src/accessor/grib_accessor_class_message_is_valid.h
+++ b/src/accessor/grib_accessor_class_message_is_valid.h
@@ -20,4 +20,7 @@ class grib_accessor_message_is_valid_t : public grib_accessor_long_t
     grib_accessor* create_empty_accessor() override { return new grib_accessor_message_is_valid_t{}; }
     int unpack_long(long* val, size_t* len) override;
     void init(const long, grib_arguments*) override;
+
+private:
+    const char* product_ = nullptr;
 };
diff --git a/tests/grib_check_message_validity.sh b/tests/grib_check_message_validity.sh
index d14b92533..f05f34139 100755
--- a/tests/grib_check_message_validity.sh
+++ b/tests/grib_check_message_validity.sh
@@ -24,8 +24,8 @@ cat >$tempFilt<<EOF
    assert ( isMessageValid == 0 );
    write;
 EOF
-${tools_dir}/grib_filter -o $tempGrib $tempFilt $sample
-
+${tools_dir}/grib_filter -o $tempGrib $tempFilt $sample 2>$tempText
+grep -q "Invalid Ni" $tempText
 grib_check_key_equals $tempGrib isMessageValid 0
 grib_check_key_equals $sample   isMessageValid 1
 
@@ -37,15 +37,16 @@ cat >$tempFilt<<EOF
    assert ( isMessageValid == 0 );
    write;
 EOF
-${tools_dir}/grib_filter -o $tempGrib $tempFilt $sample
-
+${tools_dir}/grib_filter -o $tempGrib $tempFilt $sample 2>$tempText
+grep -q "Invalid PL array" $tempText
 grib_check_key_equals $tempGrib isMessageValid 0
 
 
 # Check data values
 # ------------------------------
 ${tools_dir}/grib_set -s bitsPerValue=25 $data_dir/sample.grib2 $tempGrib
-grib_check_key_equals $tempGrib isMessageValid 0
+grib_check_key_equals $tempGrib isMessageValid 0 2>$tempText
+grep -q "Data section size mismatch" $tempText
 
 
 # Clean up