diff --git a/src/testMod/java/dan200/computercraft/ingame/ModemTest.kt b/src/testMod/java/dan200/computercraft/ingame/ModemTest.kt
index 5a3e417b2..552151a09 100644
--- a/src/testMod/java/dan200/computercraft/ingame/ModemTest.kt
+++ b/src/testMod/java/dan200/computercraft/ingame/ModemTest.kt
@@ -22,4 +22,10 @@ fun Gains_peripherals(helper: GameTestHelper) = helper.sequence {
             }
             .thenComputerOk()
     }
+
+    /**
+     * Sends a modem message to another computer on the same network
+     */
+    @GameTest
+    fun Transmits_messages(context: GameTestHelper) = context.sequence { thenComputerOk("receive") }
 }
diff --git a/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.receive.lua b/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.receive.lua
new file mode 100644
index 000000000..7a2daa82b
--- /dev/null
+++ b/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.receive.lua
@@ -0,0 +1,10 @@
+local modem = peripheral.find("modem")
+modem.open(12)
+
+
+local _, name, chan, reply, payload, distance = os.pullEvent("modem_message")
+test.eq("left", name, "Modem name")
+test.eq(12, chan, "Channel")
+test.eq(34, reply, "Reply channel")
+test.eq("Hello!", payload, "Payload")
+test.eq(4, distance, "Distance") -- Why 4?!
diff --git a/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.send.lua b/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.send.lua
new file mode 100644
index 000000000..0d36bb1a0
--- /dev/null
+++ b/src/testMod/server-files/computers/computer/0/tests/modem_test.transmits_messages.send.lua
@@ -0,0 +1,5 @@
+local modem = peripheral.find("modem")
+while true do
+    modem.transmit(12, 34, "Hello!")
+    sleep(1)
+end
diff --git a/src/testMod/server-files/structures/modem_test.transmits_messages.snbt b/src/testMod/server-files/structures/modem_test.transmits_messages.snbt
new file mode 100644
index 000000000..cb6945577
--- /dev/null
+++ b/src/testMod/server-files/structures/modem_test.transmits_messages.snbt
@@ -0,0 +1,588 @@
+{
+    size: [5, 5, 5],
+    entities: [],
+    blocks: [
+        {
+            pos: [0, 0, 0],
+            state: 0
+        },
+        {
+            pos: [0, 0, 1],
+            state: 0
+        },
+        {
+            pos: [0, 0, 2],
+            state: 0
+        },
+        {
+            pos: [0, 0, 3],
+            state: 0
+        },
+        {
+            pos: [0, 0, 4],
+            state: 0
+        },
+        {
+            pos: [1, 0, 0],
+            state: 0
+        },
+        {
+            pos: [1, 0, 1],
+            state: 0
+        },
+        {
+            pos: [1, 0, 2],
+            state: 0
+        },
+        {
+            pos: [1, 0, 3],
+            state: 0
+        },
+        {
+            pos: [1, 0, 4],
+            state: 0
+        },
+        {
+            pos: [2, 0, 0],
+            state: 0
+        },
+        {
+            pos: [2, 0, 1],
+            state: 0
+        },
+        {
+            pos: [2, 0, 2],
+            state: 0
+        },
+        {
+            pos: [2, 0, 3],
+            state: 0
+        },
+        {
+            pos: [2, 0, 4],
+            state: 0
+        },
+        {
+            pos: [3, 0, 0],
+            state: 0
+        },
+        {
+            pos: [3, 0, 1],
+            state: 0
+        },
+        {
+            pos: [3, 0, 2],
+            state: 0
+        },
+        {
+            pos: [3, 0, 3],
+            state: 0
+        },
+        {
+            pos: [3, 0, 4],
+            state: 0
+        },
+        {
+            pos: [4, 0, 0],
+            state: 0
+        },
+        {
+            pos: [4, 0, 1],
+            state: 0
+        },
+        {
+            pos: [4, 0, 2],
+            state: 0
+        },
+        {
+            pos: [4, 0, 3],
+            state: 0
+        },
+        {
+            pos: [4, 0, 4],
+            state: 0
+        },
+        {
+            pos: [0, 1, 0],
+            state: 1
+        },
+        {
+            pos: [0, 1, 1],
+            state: 1
+        },
+        {
+            pos: [0, 1, 2],
+            state: 1
+        },
+        {
+            pos: [0, 1, 3],
+            state: 1
+        },
+        {
+            pos: [0, 1, 4],
+            state: 1
+        },
+        {
+            pos: [1, 1, 0],
+            state: 1
+        },
+        {
+            pos: [1, 1, 1],
+            state: 1
+        },
+        {
+            pos: [1, 1, 2],
+            state: 1
+        },
+        {
+            pos: [1, 1, 4],
+            state: 1
+        },
+        {
+            pos: [2, 1, 0],
+            state: 1
+        },
+        {
+            pos: [2, 1, 4],
+            state: 1
+        },
+        {
+            pos: [3, 1, 0],
+            state: 1
+        },
+        {
+            pos: [3, 1, 2],
+            state: 1
+        },
+        {
+            pos: [3, 1, 3],
+            state: 1
+        },
+        {
+            pos: [3, 1, 4],
+            state: 1
+        },
+        {
+            pos: [4, 1, 0],
+            state: 1
+        },
+        {
+            pos: [4, 1, 1],
+            state: 1
+        },
+        {
+            pos: [4, 1, 2],
+            state: 1
+        },
+        {
+            pos: [4, 1, 3],
+            state: 1
+        },
+        {
+            pos: [4, 1, 4],
+            state: 1
+        },
+        {
+            pos: [0, 2, 0],
+            state: 1
+        },
+        {
+            pos: [0, 2, 1],
+            state: 1
+        },
+        {
+            pos: [0, 2, 2],
+            state: 1
+        },
+        {
+            pos: [0, 2, 3],
+            state: 1
+        },
+        {
+            pos: [0, 2, 4],
+            state: 1
+        },
+        {
+            pos: [1, 2, 0],
+            state: 1
+        },
+        {
+            pos: [1, 2, 1],
+            state: 1
+        },
+        {
+            pos: [1, 2, 2],
+            state: 1
+        },
+        {
+            pos: [1, 2, 3],
+            state: 1
+        },
+        {
+            pos: [1, 2, 4],
+            state: 1
+        },
+        {
+            pos: [2, 2, 0],
+            state: 1
+        },
+        {
+            pos: [2, 2, 1],
+            state: 1
+        },
+        {
+            pos: [2, 2, 2],
+            state: 1
+        },
+        {
+            pos: [2, 2, 3],
+            state: 1
+        },
+        {
+            pos: [2, 2, 4],
+            state: 1
+        },
+        {
+            pos: [3, 2, 0],
+            state: 1
+        },
+        {
+            pos: [3, 2, 1],
+            state: 1
+        },
+        {
+            pos: [3, 2, 2],
+            state: 1
+        },
+        {
+            pos: [3, 2, 3],
+            state: 1
+        },
+        {
+            pos: [3, 2, 4],
+            state: 1
+        },
+        {
+            pos: [4, 2, 0],
+            state: 1
+        },
+        {
+            pos: [4, 2, 1],
+            state: 1
+        },
+        {
+            pos: [4, 2, 2],
+            state: 1
+        },
+        {
+            pos: [4, 2, 3],
+            state: 1
+        },
+        {
+            pos: [4, 2, 4],
+            state: 1
+        },
+        {
+            pos: [0, 3, 0],
+            state: 1
+        },
+        {
+            pos: [0, 3, 1],
+            state: 1
+        },
+        {
+            pos: [0, 3, 2],
+            state: 1
+        },
+        {
+            pos: [0, 3, 3],
+            state: 1
+        },
+        {
+            pos: [0, 3, 4],
+            state: 1
+        },
+        {
+            pos: [1, 3, 0],
+            state: 1
+        },
+        {
+            pos: [1, 3, 1],
+            state: 1
+        },
+        {
+            pos: [1, 3, 2],
+            state: 1
+        },
+        {
+            pos: [1, 3, 3],
+            state: 1
+        },
+        {
+            pos: [1, 3, 4],
+            state: 1
+        },
+        {
+            pos: [2, 3, 0],
+            state: 1
+        },
+        {
+            pos: [2, 3, 1],
+            state: 1
+        },
+        {
+            pos: [2, 3, 2],
+            state: 1
+        },
+        {
+            pos: [2, 3, 3],
+            state: 1
+        },
+        {
+            pos: [2, 3, 4],
+            state: 1
+        },
+        {
+            pos: [3, 3, 0],
+            state: 1
+        },
+        {
+            pos: [3, 3, 1],
+            state: 1
+        },
+        {
+            pos: [3, 3, 2],
+            state: 1
+        },
+        {
+            pos: [3, 3, 3],
+            state: 1
+        },
+        {
+            pos: [3, 3, 4],
+            state: 1
+        },
+        {
+            pos: [4, 3, 0],
+            state: 1
+        },
+        {
+            pos: [4, 3, 1],
+            state: 1
+        },
+        {
+            pos: [4, 3, 2],
+            state: 1
+        },
+        {
+            pos: [4, 3, 3],
+            state: 1
+        },
+        {
+            pos: [4, 3, 4],
+            state: 1
+        },
+        {
+            pos: [0, 4, 0],
+            state: 1
+        },
+        {
+            pos: [0, 4, 1],
+            state: 1
+        },
+        {
+            pos: [0, 4, 2],
+            state: 1
+        },
+        {
+            pos: [0, 4, 3],
+            state: 1
+        },
+        {
+            pos: [0, 4, 4],
+            state: 1
+        },
+        {
+            pos: [1, 4, 0],
+            state: 1
+        },
+        {
+            pos: [1, 4, 1],
+            state: 1
+        },
+        {
+            pos: [1, 4, 2],
+            state: 1
+        },
+        {
+            pos: [1, 4, 3],
+            state: 1
+        },
+        {
+            pos: [1, 4, 4],
+            state: 1
+        },
+        {
+            pos: [2, 4, 0],
+            state: 1
+        },
+        {
+            pos: [2, 4, 1],
+            state: 1
+        },
+        {
+            pos: [2, 4, 2],
+            state: 1
+        },
+        {
+            pos: [2, 4, 3],
+            state: 1
+        },
+        {
+            pos: [2, 4, 4],
+            state: 1
+        },
+        {
+            pos: [3, 4, 0],
+            state: 1
+        },
+        {
+            pos: [3, 4, 1],
+            state: 1
+        },
+        {
+            pos: [3, 4, 2],
+            state: 1
+        },
+        {
+            pos: [3, 4, 3],
+            state: 1
+        },
+        {
+            pos: [3, 4, 4],
+            state: 1
+        },
+        {
+            pos: [4, 4, 0],
+            state: 1
+        },
+        {
+            pos: [4, 4, 1],
+            state: 1
+        },
+        {
+            pos: [4, 4, 2],
+            state: 1
+        },
+        {
+            pos: [4, 4, 3],
+            state: 1
+        },
+        {
+            pos: [4, 4, 4],
+            state: 1
+        },
+        {
+            nbt: {
+                Label: "modem_test.transmits_messages.receive",
+                id: "computercraft:computer_advanced",
+                ComputerId: 0,
+                On: 1b
+            },
+            pos: [1, 1, 3],
+            state: 2
+        },
+        {
+            nbt: {
+                PeirpheralAccess: 0b,
+                id: "computercraft:cable"
+            },
+            pos: [2, 1, 1],
+            state: 3
+        },
+        {
+            nbt: {
+                PeirpheralAccess: 0b,
+                id: "computercraft:cable"
+            },
+            pos: [2, 1, 2],
+            state: 4
+        },
+        {
+            nbt: {
+                PeirpheralAccess: 0b,
+                id: "computercraft:cable"
+            },
+            pos: [2, 1, 3],
+            state: 5
+        },
+        {
+            nbt: {
+                Label: "modem_test.transmits_messages.send",
+                id: "computercraft:computer_advanced",
+                ComputerId: 0,
+                On: 1b
+            },
+            pos: [3, 1, 1],
+            state: 2
+        }
+    ],
+    palette: [
+        {
+            Name: "minecraft:polished_andesite"
+        },
+        {
+            Name: "minecraft:air"
+        },
+        {
+            Properties: {
+                facing: "north",
+                state: "blinking"
+            },
+            Name: "computercraft:computer_advanced"
+        },
+        {
+            Properties: {
+                east: "true",
+                waterlogged: "false",
+                south: "true",
+                north: "false",
+                west: "false",
+                modem: "east_off",
+                up: "false",
+                cable: "true",
+                down: "false"
+            },
+            Name: "computercraft:cable"
+        },
+        {
+            Properties: {
+                east: "false",
+                waterlogged: "false",
+                south: "true",
+                north: "true",
+                west: "false",
+                modem: "none",
+                up: "false",
+                cable: "true",
+                down: "false"
+            },
+            Name: "computercraft:cable"
+        },
+        {
+            Properties: {
+                east: "false",
+                waterlogged: "false",
+                south: "false",
+                north: "true",
+                west: "true",
+                modem: "west_off",
+                up: "false",
+                cable: "true",
+                down: "false"
+            },
+            Name: "computercraft:cable"
+        }
+    ],
+    DataVersion: 2586
+}