diff --git a/tools/testing/selftests/net/rds/test.py b/tools/testing/selftests/net/rds/test.py
index 08f2a846a8ab..9e4df01cb0d4 100755
--- a/tools/testing/selftests/net/rds/test.py
+++ b/tools/testing/selftests/net/rds/test.py
@@ -59,6 +59,14 @@ rdma_addrs = [
 OP_FLAG_TCP     = 0x1
 OP_FLAG_RDMA    = 0x2
 
+# from include/uapi/linux/rds.h: SO_RDS_TRANSPORT pins a socket to a
+# specific RDS transport so connection setup cannot silently fall back
+# to another (e.g. loopback) transport.
+SOL_RDS          = 276
+SO_RDS_TRANSPORT = 8
+RDS_TRANS_TCP    = 2
+RDS_TRANS_IB     = 0
+
 signal_handler_label = ""
 
 tap_idx = 0
@@ -214,11 +222,21 @@ def snd_rcv_packets(env):
             netns_socket(netns_list[0], socket.AF_RDS, socket.SOCK_SEQPACKET),
             netns_socket(netns_list[1], socket.AF_RDS, socket.SOCK_SEQPACKET),
         ]
+
+        # Pin the sockets to the TCP transport so it doesn't fail over to a
+        # different transport during this test
+        for s in sockets:
+            s.setsockopt(SOL_RDS, SO_RDS_TRANSPORT, RDS_TRANS_TCP)
     elif flags & OP_FLAG_RDMA:
         sockets = [
             socket.socket(socket.AF_RDS, socket.SOCK_SEQPACKET),
             socket.socket(socket.AF_RDS, socket.SOCK_SEQPACKET),
         ]
+
+        # Pin the sockets to the RDMA transport so it doesn't fail over to a
+        # different transport during this test
+        for s in sockets:
+            s.setsockopt(SOL_RDS, SO_RDS_TRANSPORT, RDS_TRANS_IB)
     else:
         raise RuntimeError(f"Invalid transport flag sets no transports: {flags}")