diff --git a/cpu-arm.c b/cpu-arm.c
index 91c9a14..8b5d325 100644
--- a/cpu-arm.c
+++ b/cpu-arm.c
@@ -7,7 +7,20 @@
 
 #if defined TEACUP_C_INCLUDE && defined __ARMEL__
 
+#include "config_wrapper.h"
+
 void cpu_init() {
+  /**
+    Other than on ATmegas, the LPC11xx disables all peripherals except GPIO
+    and SPI0 on reset. Brown Out detector is set to kick in at 1.46 V, without
+    causing a reset. See chapter 3.5.14 in the LPC11xx User Manual.
+
+    GPIO is needed in all configurations, so we just turn off SPI0 if not
+    needed.
+  */
+  #ifndef SPI
+    LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 11);
+  #endif
 }
 
 #endif /* defined TEACUP_C_INCLUDE && defined __ARMEL__ */