diff --git a/nimble/host/src/ble_sm_cmd.c b/nimble/host/src/ble_sm_cmd.c
index b84df1ec7..a740dc3ac 100644
--- a/nimble/host/src/ble_sm_cmd.c
+++ b/nimble/host/src/ble_sm_cmd.c
@@ -29,18 +29,20 @@ void *
 ble_sm_cmd_get(uint8_t opcode, size_t len, struct os_mbuf **txom)
 {
     struct ble_sm_hdr *hdr;
+    void *data;
 
     *txom = ble_hs_mbuf_l2cap_pkt();
     if (*txom == NULL) {
         return NULL;
     }
 
-    if (os_mbuf_extend(*txom, sizeof(*hdr) + len) == NULL) {
+    data = os_mbuf_extend(*txom, sizeof(*hdr) + len);
+    if (data == NULL) {
         os_mbuf_free_chain(*txom);
         return NULL;
     }
 
-    hdr = (struct ble_sm_hdr *)(*txom)->om_data;
+    hdr = (struct ble_sm_hdr *)data;
 
     hdr->opcode = opcode;