diff --git a/src/libs/zbxpreproc/pp_protocol.c b/src/libs/zbxpreproc/pp_protocol.c
index 822eb4ed4b8..5595846ebed 100644
--- a/src/libs/zbxpreproc/pp_protocol.c
+++ b/src/libs/zbxpreproc/pp_protocol.c
@@ -1171,6 +1171,13 @@ void	zbx_preprocess_item_value(zbx_uint64_t itemid, unsigned char item_value_typ
 			else if (ZBX_ISSET_DBL(result) || ZBX_ISSET_UI64(result))
 			{
 				/* double and uint are valid JSON and do not require limit checks */
+				/* except when double is NaN                                      */
+				if (ZBX_ISSET_DBL(result) && FAIL == zbx_validate_value_dbl(result->dbl))
+				{
+					state = ITEM_STATE_NOTSUPPORTED;
+					error = zbx_strdup(NULL, "NaN is not a valid JSON");
+				}
+
 				zbx_dc_add_history(itemid, item_value_type, item_flags, result, ts, state, error);
 				goto out;
 			}