diff --git a/pkg/distributor/validator.go b/pkg/distributor/validator.go
index 1b816de4ac2ba..933ff5201937b 100644
--- a/pkg/distributor/validator.go
+++ b/pkg/distributor/validator.go
@@ -12,6 +12,7 @@ import (
 	"github.com/grafana/loki/pkg/logproto"
 	"github.com/grafana/loki/pkg/util"
 	"github.com/grafana/loki/pkg/util/flagext"
+	"github.com/grafana/loki/pkg/util/validation"
 )
 
 type Validator struct {
@@ -38,6 +39,7 @@ func (v Validator) ValidateEntry(userID string, entry logproto.Entry) error {
 		// an orthogonal concept (we need not use ValidateLabels in this context)
 		// but the upstream cortex_validation pkg uses it, so we keep this
 		// for parity.
+		validation.DiscardedSamples.WithLabelValues(validation.LineTooLong, userID).Inc()
 		return httpgrpc.Errorf(
 			http.StatusBadRequest,
 			"max line size (%s) exceeded while adding (%s) size line",
diff --git a/pkg/util/validation/validate.go b/pkg/util/validation/validate.go
index 8c59fdc828c5a..9293a989c17fb 100644
--- a/pkg/util/validation/validate.go
+++ b/pkg/util/validation/validate.go
@@ -8,6 +8,8 @@ const (
 	// RateLimited is one of the values for the reason to discard samples.
 	// Declared here to avoid duplication in ingester and distributor.
 	RateLimited = "rate_limited"
+	// LineTooLong is a reason for discarding too long log lines.
+	LineTooLong = "line_too_long"
 )
 
 // DiscardedBytes is a metric of the total discarded bytes, by reason.