diff --git a/scripts/perf-tests/test/test_run_perf_tests.sh b/scripts/perf-tests/test/test_run_perf_tests.sh
index 6531563..cce59e2 100755
--- a/scripts/perf-tests/test/test_run_perf_tests.sh
+++ b/scripts/perf-tests/test/test_run_perf_tests.sh
@@ -81,6 +81,15 @@ if [[ "$ACMD" == *"--lro-disable"* ]]; then ok "astf launch includes --lro-disab
 if [[ "$SCMD" == *"--lro-disable"* ]]; then ok "stl launch includes --lro-disable"; else bad "stl launch includes --lro-disable"; fi
 if [[ "$SCMD" != *"--astf"* ]]; then ok "stl mode omits --astf"; else bad "stl mode omits --astf"; fi
 
+echo "== run_tcp_benchmark.py: ASTFIPGenDist ip_range must be a [start,end] list =="
+TCP_PY="$TEST_DIR/../trex/run_tcp_benchmark.py"
+if grep -nE 'ASTFIPGenDist\(ip_range=' "$TCP_PY" | grep -qvE 'ip_range=\['; then
+    bad "ASTFIPGenDist uses a single-IP ip_range (TRex needs [start,end]):"
+    grep -nE 'ASTFIPGenDist\(ip_range=' "$TCP_PY" | grep -vE 'ip_range=\['
+else
+    ok "all ASTFIPGenDist ip_range args are lists"
+fi
+
 # ── 3. TRex mode selection: stl for UDP, astf for any *-tcp ───────────────────
 echo "== TRex STL/ASTF mode selection =="
 for c in "rust-dpdk-tcp,tokio-dpdk-tcp,plain-rust-tcp" "rust-dpdk-tcp"; do
diff --git a/scripts/perf-tests/trex/run_tcp_benchmark.py b/scripts/perf-tests/trex/run_tcp_benchmark.py
index bc1efa5..9c8888f 100644
--- a/scripts/perf-tests/trex/run_tcp_benchmark.py
+++ b/scripts/perf-tests/trex/run_tcp_benchmark.py
@@ -49,10 +49,13 @@ def build_tcp_profile(payload_size, src_ip, dst_ip, dst_port):
     prog_s.recv(payload_size)
     prog_s.send(payload)
 
-    ip_gen_c = ASTFIPGenDist(ip_range=src_ip, distribution="seq")
-    ip_gen_s = ASTFIPGenDist(ip_range=dst_ip, distribution="seq")
+    # TRex ASTFIPGenDist requires a 2-element [start, end] range, even for a
+    # single host — pass [ip, ip]. A bare string fails ArgVerify with
+    # "Bad IP range ... Range should contain two IPs".
+    ip_gen_c = ASTFIPGenDist(ip_range=[src_ip, src_ip], distribution="seq")
+    ip_gen_s = ASTFIPGenDist(ip_range=[dst_ip, dst_ip], distribution="seq")
     ip_gen = ASTFIPGen(
-        glob=ASTFIPGenDist(ip_range="0.0.0.0", distribution="seq"),
+        glob=ASTFIPGenDist(ip_range=["0.0.0.0", "0.0.0.0"], distribution="seq"),
         dist_client=ip_gen_c,
         dist_server=ip_gen_s,
     )