diff --git a/include/libsigrok/libsigrok.h b/include/libsigrok/libsigrok.h
index e1320124..e03fedc5 100644
--- a/include/libsigrok/libsigrok.h
+++ b/include/libsigrok/libsigrok.h
@@ -231,6 +231,8 @@ enum sr_mq {
 	SR_MQ_APPARENT_POWER,
 	/** Mass */
 	SR_MQ_MASS,
+	/** Harmonic ratio */
+	SR_MQ_HARMONIC_RATIO,
 
 	/* Update sr_key_info_mq[] (hwdriver.c) upon changes! */
 };
diff --git a/src/hwdriver.c b/src/hwdriver.c
index ab221010..20fc3bb9 100644
--- a/src/hwdriver.c
+++ b/src/hwdriver.c
@@ -247,6 +247,7 @@ static struct sr_key_info sr_key_info_mq[] = {
 	{SR_MQ_POWER_FACTOR, 0, "power_factor", "Power factor", NULL},
 	{SR_MQ_APPARENT_POWER, 0, "apparent_power", "Apparent power", NULL},
 	{SR_MQ_MASS, 0, "mass", "Mass", NULL},
+	{SR_MQ_HARMONIC_RATIO, 0, "harmonic_ratio", "Harmonic ratio", NULL},
 	ALL_ZERO
 };