diff --git a/avr/libraries/Wire/src/SoftI2CMaster.h b/avr/libraries/Wire/src/SoftI2CMaster.h
index 30eb4cbe..0c61a2cf 100644
--- a/avr/libraries/Wire/src/SoftI2CMaster.h
+++ b/avr/libraries/Wire/src/SoftI2CMaster.h
@@ -199,7 +199,6 @@ void  i2c_delay_half(void)
   __asm__ __volatile__ (" ret");
   // 7 cycles for call and return
 #else
-  uint8_t temp = 0;
   __asm__ __volatile__
     (
      " ldi      r25, %[DELAY]           ; load delay constant   ; 4C \n\t"
@@ -207,7 +206,7 @@ void  i2c_delay_half(void)
      " dec r25                          ; decrement counter     ; 4C + xC \n\t"
      " brne _Lidelay                                           ; 5C+(x-1)2C + xC\n\t"
      " ret                                                     ; 9C+(x-1)2C + xC = 7C + xC"
-     :"+d" ((uint8_t) temp) : [DELAY] "M" I2C_DELAY_COUNTER);
+    : : [DELAY] "M" I2C_DELAY_COUNTER : "r25");
   // 7 cycles + 3 times x cycles
 #endif
 }
diff --git a/avr/libraries/Wire/src/SoftWire.h b/avr/libraries/Wire/src/SoftWire.h
index 91e5f8e7..b1341e1c 100644
--- a/avr/libraries/Wire/src/SoftWire.h
+++ b/avr/libraries/Wire/src/SoftWire.h
@@ -113,11 +113,11 @@ class SoftWire : public Stream
       beginTransmission(address);
       // the maximum size of internal address is 3 bytes
       if (isize > 3) {
-  isize = 3;
+          isize = 3;
       }
       // write internal register address - most significant byte first
       while (isize-- > 0)
-  write((uint8_t)(iaddress >> (isize*8)));
+          write((uint8_t)(iaddress >> (isize*8)));
       endTransmission(false);
     }
     // clamp to buffer length
diff --git a/avr/libraries/Wire/src/Wire.cpp b/avr/libraries/Wire/src/Wire.cpp
index 80f443fb..b9c5aeec 100644
--- a/avr/libraries/Wire/src/Wire.cpp
+++ b/avr/libraries/Wire/src/Wire.cpp
@@ -732,10 +732,9 @@
       return value;
     }
   #else // Implementations for slave only mode
-    void TwoWire::begin(int address) {
-      begin((uint8_t)address);
+void TwoWire::begin(uint8_t address) {
+      TinyWireS.begin((uint8_t)address, 0);
     }
-
     // must be called in slave onRequest event callback
     size_t TwoWire::write(uint8_t data) {
       size_t numBytes = 0;
@@ -814,7 +813,7 @@
   /* END MASTER ONLY METHODS */
 
   /* BEGIN SLAVE ONLY METHODS */
-  #if defined(SLAVE_MASTER_ONLY) || defined(WIRE_BOTH)
+  #if defined(WIRE_SLAVE_ONLY) || defined(WIRE_BOTH)
 
     void TwoWire::onReceive( void (*function)(size_t)) {
       TinyWireS.onReceive(function);
@@ -822,7 +821,7 @@
     void TwoWire::onReceive( void (*function)(int)) {
       // arduino api compatibility fixer:
       // really hope size parameter will not exceed 2^31 :)
-      static_assert(sizeof(int) == sizeof(size_t), "something is wrong in Arduino kingdom");
+      static_assert(sizeof(int) == sizeof(size_t), "something is wrong in the Arduino kingdom");
       TinyWireS.onReceive(reinterpret_cast<void(*)(size_t)>(function));
     }
     // sets function called on slave read
diff --git a/avr/variants/tinyx41_cw/pins_arduino.h b/avr/variants/tinyx41_cw/pins_arduino.h
index 2609dee1..db2c2725 100644
--- a/avr/variants/tinyx41_cw/pins_arduino.h
+++ b/avr/variants/tinyx41_cw/pins_arduino.h
@@ -292,13 +292,13 @@ anyway) and instead just use TOCPMCOE bits to control whether PWM is output */
  * a markedly inferior software TWI master implementation if that is requested.
  *---------------------------------------------------------------------------*/
 
-/* Hardware I2C slave */
-#define SCL                      PIN_PA6
+/* Used by hardware I2C slave and software I2C master */
+#define SCL                      PIN_PA4
 #define SCL_PORT                 (PORTA)
-#define SCL_PIN                  (6)
-#define SDA                      PIN_PA4
+#define SCL_PIN                  (4)
+#define SDA                      PIN_PA6
 #define SDA_PORT                 (PORTA)
-#define SDA_PIN                  (4)
+#define SDA_PIN                  (6)
 
 /* Hardware SPI */
 #if defined(SET_REMAP) && SET_REMAP > 1
diff --git a/avr/variants/tinyx41_legacy/pins_arduino.h b/avr/variants/tinyx41_legacy/pins_arduino.h
index beec9fce..b0d84d6a 100644
--- a/avr/variants/tinyx41_legacy/pins_arduino.h
+++ b/avr/variants/tinyx41_legacy/pins_arduino.h
@@ -293,13 +293,13 @@ anyway) and instead just use TOCPMCOE bits to control whether PWM is output */
  * a markedly inferior software TWI master implementation if that is requested.
  *---------------------------------------------------------------------------*/
 
-/* Hardware I2C slave */
-#define SCL                      PIN_PA6
+/* Used by hardware I2C slave and software I2C master */
+#define SCL                      PIN_PA4
 #define SCL_PORT                 (PORTA)
-#define SCL_PIN                  (6)
-#define SDA                      PIN_PA4
+#define SCL_PIN                  (4)
+#define SDA                      PIN_PA6
 #define SDA_PORT                 (PORTA)
-#define SDA_PIN                  (4)
+#define SDA_PIN                  (6)
 
 /* Hardware SPI */
 #if defined(SET_REMAP) && SET_REMAP > 1