diff --git a/firmware/mcp_adc.c b/firmware/mcp_adc.c
index addc539..04e0f83 100644
--- a/firmware/mcp_adc.c
+++ b/firmware/mcp_adc.c
@@ -21,6 +21,8 @@
 
 #define ADC_ADDR 0xD0 /* or 0x68 */
 
+uint8_t r[4];
+
 void mcpadc_init(uint8_t mode)
 {
 	i2c_write(ADC_ADDR, 1, &mode);
@@ -28,7 +30,6 @@ void mcpadc_init(uint8_t mode)
 
 uint8_t mcpadc_has_new_data()
 {
-	uint8_t r[4];
 	i2c_read(ADC_ADDR, 4, r);/* 4 bytes are only needed in 18 bit mode */
 	return(r[3] & ADC_NEW_SAMPLE);
 }
@@ -36,7 +37,6 @@ uint8_t mcpadc_has_new_data()
 #if ADC_ENABLE_18_BIT_MODE
 int32_t mcpadc_get_data()
 {
-	uint8_t r[4] = {0,0,0,0};
 	int32_t value = 0;
 	i2c_read(ADC_ADDR, 4, r);/* reading 4 bytes guarantees us one config byte */
 	if(r[0] & 0x80) {value = 0xffff;}
@@ -50,7 +50,6 @@ int32_t mcpadc_get_data()
 #else
 int16_t mcpadc_get_data()
 {
-	uint8_t r[2] = {0,0};
 	i2c_read(ADC_ADDR, 2, r);/* this will NOT work in 18 bit mode */
 	int16_t value = (r[0] << 8) | r[1];/*endianess ???*/
 	return r;
@@ -59,7 +58,6 @@ int16_t mcpadc_get_data()
 
 void mcpadc_start_conv()
 {
-	uint8_t r[4];
 	i2c_read(ADC_ADDR, 4, r);
 	r[3] |= ADC_NEW_SAMPLE;
 	i2c_write(ADC_ADDR, 1, &(r[3]));