diff --git a/rtc_base/experiments/field_trial_parser.cc b/rtc_base/experiments/field_trial_parser.cc
index b88d0f97c4..8fc89cec8f 100644
--- a/rtc_base/experiments/field_trial_parser.cc
+++ b/rtc_base/experiments/field_trial_parser.cc
@@ -83,7 +83,10 @@ void ParseFieldTrial(
         RTC_LOG(LS_WARNING) << "Failed to read empty key field with value '"
                             << key << "' in trial: \"" << trial_string << "\"";
       }
-    } else {
+    } else if (key.empty() || key[0] != '_') {
+      // "_" is be used to prefix keys that are part of the string for
+      // debugging purposes but not neccessarily used.
+      // e.g. WebRTC-Experiment/param: value, _DebuggingString
       RTC_LOG(LS_INFO) << "No field with key: '" << key
                        << "' (found in trial: \"" << trial_string << "\")";
       std::string valid_keys;
diff --git a/rtc_base/experiments/struct_parameters_parser.cc b/rtc_base/experiments/struct_parameters_parser.cc
index 2605da8fef..d62eb6f1ea 100644
--- a/rtc_base/experiments/struct_parameters_parser.cc
+++ b/rtc_base/experiments/struct_parameters_parser.cc
@@ -107,7 +107,10 @@ void StructParametersParser::Parse(absl::string_view src) {
         break;
       }
     }
-    if (!found) {
+    // "_" is be used to prefix keys that are part of the string for
+    // debugging purposes but not neccessarily used.
+    // e.g. WebRTC-Experiment/param: value, _DebuggingString
+    if (!found && (key.empty() || key[0] != '_')) {
       RTC_LOG(LS_INFO) << "No field with key: '" << key
                        << "' (found in trial: \"" << src << "\")";
     }