diff --git a/checker/rules_rtt.go b/checker/rules_rtt.go
index a6be757..5ef851e 100644
--- a/checker/rules_rtt.go
+++ b/checker/rules_rtt.go
@@ -28,6 +28,14 @@ import (
 	sdk "git.happydns.org/checker-sdk-go/checker"
 )
 
+// Default RTT thresholds in milliseconds. These sit above ordinary
+// cross-region internet latency (e.g. transatlantic RTTs of ~100ms) so
+// that healthy long-haul targets do not trigger spurious warnings.
+const (
+	defaultWarningRTT  = 200.0
+	defaultCriticalRTT = 500.0
+)
+
 // rttRule evaluates the average round-trip time of each target against
 // the configured warning/critical thresholds. Unreachable targets (no
 // reply at all) are skipped; the reachability rule handles those.
@@ -39,8 +47,8 @@ func (r *rttRule) Description() string {
 }
 
 func (r *rttRule) ValidateOptions(opts sdk.CheckerOptions) error {
-	warn := sdk.GetFloatOption(opts, "warningRTT", 100)
-	crit := sdk.GetFloatOption(opts, "criticalRTT", 500)
+	warn := sdk.GetFloatOption(opts, "warningRTT", defaultWarningRTT)
+	crit := sdk.GetFloatOption(opts, "criticalRTT", defaultCriticalRTT)
 	if warn <= 0 {
 		return fmt.Errorf("warningRTT must be positive")
 	}
@@ -59,8 +67,8 @@ func (r *rttRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts
 		return []sdk.CheckState{noTargetsState("ping.rtt.no_targets")}
 	}
 
-	warn := sdk.GetFloatOption(opts, "warningRTT", 100)
-	crit := sdk.GetFloatOption(opts, "criticalRTT", 500)
+	warn := sdk.GetFloatOption(opts, "warningRTT", defaultWarningRTT)
+	crit := sdk.GetFloatOption(opts, "criticalRTT", defaultCriticalRTT)
 
 	out := make([]sdk.CheckState, 0, len(data.Targets))
 	for _, t := range data.Targets {