diff --git a/cubesatsim/cubesatsim.ino b/cubesatsim/cubesatsim.ino
index b8e180dc..9c051f38 100644
--- a/cubesatsim/cubesatsim.ino
+++ b/cubesatsim/cubesatsim.ino
@@ -3549,7 +3549,7 @@ void config_gpio() {
   pinMode(BPF_PIN, INPUT_PULLUP);  // Read LPF to see if present
 //  pinMode(SQUELCH, INPUT);	// Squelch from TXC
 
-  if (digitalRead(BPF_PIN) == FALSE) {
+  if (digitalRead(BPF_PIN) != FALSE) {  // force BPF present
     Serial.println("BPF present - transmit enabled");
     filter_present = true;  
   }