diff --git a/src/uct/ib/dc/accel/dc_mlx5.c b/src/uct/ib/dc/accel/dc_mlx5.c
index 52fee4ad561..0b25d4febca 100644
--- a/src/uct/ib/dc/accel/dc_mlx5.c
+++ b/src/uct/ib/dc/accel/dc_mlx5.c
@@ -657,7 +657,7 @@ ucs_status_t uct_dc_mlx5_ep_tag_eager_zcopy(uct_ep_h tl_ep, uct_tag_t tag,
     UCT_RC_IFACE_FILL_TM_IMM(imm, app_ctx, ib_imm, opcode, MLX5_OPCODE_SEND, _IMM);
 
     uct_dc_mlx5_iface_zcopy_post(iface, ep, opcode|UCT_RC_MLX5_OPCODE_FLAG_TM,
-                                 iov, iovcnt, 0, NULL, 0, 0, 0, tag, app_ctx,
+                                 iov, iovcnt, 0, "", 0, 0, 0, tag, app_ctx,
                                  ib_imm, comp, MLX5_WQE_CTRL_SOLICITED);
 
     return UCS_INPROGRESS;
diff --git a/src/uct/ib/rc/accel/rc_mlx5_ep.c b/src/uct/ib/rc/accel/rc_mlx5_ep.c
index 256f10c0816..993d7e395ef 100644
--- a/src/uct/ib/rc/accel/rc_mlx5_ep.c
+++ b/src/uct/ib/rc/accel/rc_mlx5_ep.c
@@ -489,7 +489,7 @@ ucs_status_t uct_rc_mlx5_ep_tag_eager_zcopy(uct_ep_h tl_ep, uct_tag_t tag,
                              _IMM);
 
     return uct_rc_mlx5_ep_zcopy_post(ep, opcode|UCT_RC_MLX5_OPCODE_FLAG_TM,
-                                     iov, iovcnt, 0, NULL, 0, 0, 0,
+                                     iov, iovcnt, 0, "", 0, 0, 0,
                                      tag, app_ctx, ib_imm,
                                      MLX5_WQE_CTRL_SOLICITED, comp);
 }