diff --git a/arduino/libraries/StrixFPGA/src/StrixFPGA.cpp b/arduino/libraries/StrixFPGA/src/StrixFPGA.cpp
index 74e8c22..bc6a2a6 100644
--- a/arduino/libraries/StrixFPGA/src/StrixFPGA.cpp
+++ b/arduino/libraries/StrixFPGA/src/StrixFPGA.cpp
@@ -32,6 +32,12 @@ bool StrixFPGA::begin() {
   if (!vidor.begin(true)) return false;
   delay(100);  // configuration and PLL lock
 
+  // The core configures the battery charger chip over I2C (SERCOM0 on D11/D12) at boot and leaves
+  // those pins assigned to SERCOM0. Detach them, or the SPI link's signals would also appear on
+  // the charger's I2C bus.
+  pinMode(PIN_WIRE_SDA, INPUT);
+  pinMode(PIN_WIRE_SCL, INPUT);
+
   pinMode(STRIX_SS, OUTPUT);
   digitalWrite(STRIX_SS, HIGH);
   strixSpi.begin();