diff --git a/cache/src/tango_cache_pending.cpp b/cache/src/tango_cache_pending.cpp
index 2a5d928..22a42b3 100644
--- a/cache/src/tango_cache_pending.cpp
+++ b/cache/src/tango_cache_pending.cpp
@@ -148,7 +148,7 @@ time_t absolute_to_relative_time(const char* gmt_time)
 bool  is_standard_gmt_format(const char* value)
 {
     int str_len = strlen(value);
-    if ((value[str_len - 1] == 'T') && (value[str_len - 2] == 'M') && (value[str_len - 3] == 'G'))
+	if(0==strcasecmp(value+str_len-3,"GMT"))
     {
         return true;
     }
@@ -215,9 +215,8 @@ void get_response_freshness(const struct tfe_http_half *response, struct respons
     else
     {
         field_value = tfe_http_std_field_read(response, TFE_HTTP_EXPIRES);
-        if (field_value != NULL)
+        if (field_value != NULL && is_standard_gmt_format(field_value))
         {
-            assert(is_standard_gmt_format(field_value));
             expire_rel_time = absolute_to_relative_time(field_value);
             const time_t cur_ct_time = time(NULL);
             if (gmtime_r(&cur_ct_time, &cur_gmt_time) == NULL)