diff --git a/sys/dev/mlx5/mlx5_en/mlx5_en_main.c b/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
index 951cbee61c2b..d59cf215bbdb 100644
--- a/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
+++ b/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
@@ -171,6 +171,10 @@ static const struct media mlx5e_mode_table[MLX5E_LINK_SPEEDS_NUMBER][MLX5E_LINK_
 		.subtype = IFM_50G_KR2,
 		.baudrate = IF_Gbps(50ULL),
 	},
+	[MLX5E_50GBASE_KR4][MLX5E_KR4] = {
+		.subtype = IFM_50G_KR4,
+		.baudrate = IF_Gbps(50ULL),
+	},
 };
 
 static const struct media mlx5e_ext_mode_table[MLX5E_EXT_LINK_SPEEDS_NUMBER][MLX5E_LINK_MODES_NUMBER] = {
@@ -319,6 +323,10 @@ static const struct media mlx5e_ext_mode_table[MLX5E_EXT_LINK_SPEEDS_NUMBER][MLX
 		.subtype = IFM_50G_KR2,
 		.baudrate = IF_Gbps(50ULL),
 	},
+	[MLX5E_50GAUI_2_LAUI_2_50GBASE_CR2_KR2][MLX5E_KR4] = {
+		.subtype = IFM_50G_KR4,
+		.baudrate = IF_Gbps(50ULL),
+	},
 	[MLX5E_50GAUI_2_LAUI_2_50GBASE_CR2_KR2][MLX5E_SR2] = {
 		.subtype = IFM_50G_SR2,
 		.baudrate = IF_Gbps(50ULL),
diff --git a/sys/dev/mlx5/mlx5_ib/mlx5_ib_main.c b/sys/dev/mlx5/mlx5_ib/mlx5_ib_main.c
index eec585eeeb75..d175078db594 100644
--- a/sys/dev/mlx5/mlx5_ib/mlx5_ib_main.c
+++ b/sys/dev/mlx5/mlx5_ib/mlx5_ib_main.c
@@ -199,6 +199,7 @@ static int translate_eth_proto_oper(u32 eth_proto_oper, u8 *active_speed,
 		break;
 	case MLX5E_PROT_MASK(MLX5E_50GBASE_CR2):
 	case MLX5E_PROT_MASK(MLX5E_50GBASE_KR2):
+	case MLX5E_PROT_MASK(MLX5E_50GBASE_KR4):
 	case MLX5E_PROT_MASK(MLX5E_50GBASE_SR2):
 		*active_width = IB_WIDTH_1X;
 		*active_speed = IB_SPEED_HDR;
diff --git a/sys/dev/mlx5/port.h b/sys/dev/mlx5/port.h
index 043c70388301..d46ae1303496 100644
--- a/sys/dev/mlx5/port.h
+++ b/sys/dev/mlx5/port.h
@@ -95,6 +95,7 @@ enum mlx5e_link_speed {
 	MLX5E_40GBASE_SR4	 = 15,
 	MLX5E_40GBASE_LR4_ER4	 = 16,
 	MLX5E_50GBASE_SR2	 = 18,
+	MLX5E_50GBASE_KR4	 = 19,
 	MLX5E_100GBASE_CR4	 = 20,
 	MLX5E_100GBASE_SR4	 = 21,
 	MLX5E_100GBASE_KR4	 = 22,