diff --git a/src/mesh/RadioInterface.cpp b/src/mesh/RadioInterface.cpp
index 7da9325d46f..49757b3579e 100644
--- a/src/mesh/RadioInterface.cpp
+++ b/src/mesh/RadioInterface.cpp
@@ -1481,6 +1481,17 @@ void RadioInterface::limitPower(int8_t loraMaxPower)
     if (power > loraMaxPower) // Clamp power to maximum defined level
         power = loraMaxPower;
 
+    // Floor as well as ceiling. On a board that declares an external PA gain the
+    // subtraction above can push the level below what the radio can physically
+    // emit: the chip then rejects the setting and stops transmitting altogether
+    // rather than transmitting weakly. Measured on a board with
+    // TX_GAIN_LORA 25 and tx_power -9: "Final Tx power: -34 dBm" and no packet
+    // ever left the queue.
+    if (power < RADIO_MIN_TX_POWER_DBM) {
+        LOG_WARN("Tx power %d dBm below radio minimum, raising to %d dBm", power, RADIO_MIN_TX_POWER_DBM);
+        power = RADIO_MIN_TX_POWER_DBM;
+    }
+
     LOG_INFO("Final Tx power: %d dBm", power);
 }
 
diff --git a/src/mesh/RadioInterface.h b/src/mesh/RadioInterface.h
index e76b977bf40..43814fe3595 100644
--- a/src/mesh/RadioInterface.h
+++ b/src/mesh/RadioInterface.h
@@ -17,6 +17,15 @@ typedef struct _meshtastic_Config_LoRaConfig meshtastic_Config_LoRaConfig;
 
 #define MAX_TX_QUEUE 16 // max number of packets which can be waiting for transmission
 
+// Lowest level the radio can actually emit. Below this the chip rejects the
+// setting and transmits nothing at all, so limitPower() floors here rather than
+// handing the driver an impossible value. -9 dBm covers SX126x (RadioLib's
+// SX1268::checkOutputPower allows -9..22); boards with a different floor can
+// override it in variant.h.
+#ifndef RADIO_MIN_TX_POWER_DBM
+#define RADIO_MIN_TX_POWER_DBM -9
+#endif
+
 #define MAX_LORA_PAYLOAD_LEN 255 // max length of 255 per Semtech's datasheets on SX12xx
 #define MESHTASTIC_HEADER_LENGTH 16
 #define MESHTASTIC_PKC_OVERHEAD 12