diff --git a/pigpio.c b/pigpio.c
index c9688ba..24fe287 100644
--- a/pigpio.c
+++ b/pigpio.c
@@ -25,7 +25,7 @@ OTHER DEALINGS IN THE SOFTWARE.
 For more information, please refer to <http://unlicense.org/>
 */
 
-/* pigpio version 72 */
+/* pigpio version 73 */
 
 /* include ------------------------------------------------------- */
 
diff --git a/pigpio.h b/pigpio.h
index 44b3ba5..b6547e3 100644
--- a/pigpio.h
+++ b/pigpio.h
@@ -30,7 +30,7 @@ For more information, please refer to <http://unlicense.org/>
 #include <stdint.h>
 #include <pthread.h>
 
-#define PIGPIO_VERSION 72
+#define PIGPIO_VERSION 73
 
 /*TEXT
 
@@ -702,7 +702,7 @@ typedef void *(gpioThreadFunc_t) (void *);
 /* Files, I2C, SPI, SER */
 
 #define PI_FILE_SLOTS 16
-#define PI_I2C_SLOTS  64
+#define PI_I2C_SLOTS  512
 #define PI_SPI_SLOTS  32
 #define PI_SER_SLOTS  16