diff --git a/test/schema/invalid/probelistenport-negative.expect.txt b/test/schema/invalid/probelistenport-negative.expect.txt
new file mode 100644
index 0000000..dbdcfc4
--- /dev/null
+++ b/test/schema/invalid/probelistenport-negative.expect.txt
@@ -0,0 +1 @@
+at '/probeListenPort'
diff --git a/test/schema/invalid/probelistenport-negative.yaml b/test/schema/invalid/probelistenport-negative.yaml
new file mode 100644
index 0000000..c33cce5
--- /dev/null
+++ b/test/schema/invalid/probelistenport-negative.yaml
@@ -0,0 +1 @@
+probeListenPort: -1
diff --git a/test/schema/invalid/probelistenport-too-high.expect.txt b/test/schema/invalid/probelistenport-too-high.expect.txt
new file mode 100644
index 0000000..dbdcfc4
--- /dev/null
+++ b/test/schema/invalid/probelistenport-too-high.expect.txt
@@ -0,0 +1 @@
+at '/probeListenPort'
diff --git a/test/schema/invalid/probelistenport-too-high.yaml b/test/schema/invalid/probelistenport-too-high.yaml
new file mode 100644
index 0000000..dffbfbe
--- /dev/null
+++ b/test/schema/invalid/probelistenport-too-high.yaml
@@ -0,0 +1 @@
+probeListenPort: 70000
diff --git a/test/schema/valid/probelistenport-explicit.yaml b/test/schema/valid/probelistenport-explicit.yaml
new file mode 100644
index 0000000..926b453
--- /dev/null
+++ b/test/schema/valid/probelistenport-explicit.yaml
@@ -0,0 +1,3 @@
+# Locks down the [0, 65535] range on probeListenPort. 0 = disabled
+# (default); any 1..65535 enables a separate plain-HTTP probe server.
+probeListenPort: 8081