diff --git a/api/maa.h b/api/maa.h
index 3bd5efc..7ae72ca 100644
--- a/api/maa.h
+++ b/api/maa.h
@@ -142,7 +142,8 @@ typedef struct {
  */
 typedef struct {
     /*@{*/
-    double bus_id; /**< The Bus ID as exposed to the system. */
+    unsigned int bus_id; /**< The Bus ID as exposed to the system. */
+    unsigned int slave_s; /**< Slave select */
     maa_boolean_t three_wire; /**< Is the bus only a three wire system */
     unsigned int sclk; /**< Serial Clock */
     unsigned int mosi; /**< Master Out, Slave In. */
diff --git a/src/intel_galileo_rev_d.c b/src/intel_galileo_rev_d.c
index 118e5b1..2ebf03e 100644
--- a/src/intel_galileo_rev_d.c
+++ b/src/intel_galileo_rev_d.c
@@ -261,7 +261,8 @@ maa_intel_galileo_rev_d()
 
     b->spi_bus_count = 1;
     b->def_spi_bus = 0;
-    b->spi_bus[0].bus_id = 1.0;
+    b->spi_bus[0].bus_id = 1;
+    b->spi_bus[0].slave_s = 0;
     b->spi_bus[0].cs = 10;
     b->spi_bus[0].mosi = 11;
     b->spi_bus[0].miso = 12;