diff --git a/avr/main.c b/avr/main.c
index c06762a..beaa1da 100644
--- a/avr/main.c
+++ b/avr/main.c
@@ -19,8 +19,9 @@ static const uint16_t timer_counter_intervals[4] = {
 };
 
 static volatile tabby_avr_buffer buffer = {
-    .len = 0,
-    .cur = 0
+    .len  = 0,
+    .cur  = 0,
+    .read = 0
 };
 
 static tabby_clock_source source = TABBY_CLOCK_SOURCE_INTERNAL;
@@ -50,8 +51,8 @@ ISR(TIMER0_COMPB_vect) {
         if (buffer.cur < buffer.len) {
             value_out = buffer.data[buffer.cur++];
         } else {
-            buffer.len = 0;
-            buffer.cur = 0;
+            buffer.len  = 0;
+            buffer.cur  = 0;
             buffer.read = 0;
         }
 
@@ -74,6 +75,8 @@ ISR(SPI_STC_vect) {
     if (buffer.cur < buffer.len) {
         SPDR = buffer.data[buffer.cur++];
     } else {
+        SPDR = 0xff;
+
         buffer.len  = 0;
         buffer.cur  = 0;
         buffer.read = 0;
@@ -84,17 +87,17 @@ static void setup_clock_internal(tabby_clock_speed speed) {
     /*
      * Configure MISO as output
      */
-    DDRB |= (1 << DDB3);
+    DDRB |= (1 << DDB4);
 
     /*
      * Configure MOSI as input
      */
-    DDRB &= ~(1 << DDB2);
+    DDRB &= ~(1 << DDB3);
 
     /*
      * Configure SCK pin as output
      */
-    DDRB |= (1 << DDB1);
+    DDRB |= (1 << DDB5);
 
     /*
      * Enable timer interrupt vector
@@ -128,12 +131,12 @@ static void setup_clock_external() {
     /*
      * Configure MISO as output
      */
-    DDRB |= (1 << DDB3);
+    DDRB |= (1 << DDB4);
 
     /*
-     * Configure MOSI as input
+     * Configure SS as input
      */
-    DDRB &= ~(1 << DDB3);
+    DDRB &= ~(1 << DDB2);
 
     /*
      * Set SPI slave mode, and shift in/out most significant bit first
@@ -150,8 +153,9 @@ static void setup_clock_external() {
      */
     SPDR = 0;
 
-    buffer.len = 0;
-    buffer.cur = 0;
+    buffer.len  = 0;
+    buffer.cur  = 0;
+    buffer.read = 0;
 }
 
 /*static void snooze() {
@@ -210,7 +214,7 @@ int main() {
                 break;
             }
 
-            case TABBY_COMMAND_CLOCK_SOURCE:
+            case TABBY_COMMAND_CLOCK_SOURCE: {
                 switch (c) {
                     case TABBY_CLOCK_SOURCE_INTERNAL: {
                         source = c;
@@ -232,6 +236,7 @@ int main() {
                         goto reset;
                     }
                 }
+            }
 
             case TABBY_COMMAND_CLOCK_SPEED: {
                 switch (c) {
@@ -254,7 +259,7 @@ int main() {
             }
 
             default: {
-                break;
+                goto reset;
             }
         }