diff --git a/Adafruit_BusIO_Register.cpp b/Adafruit_BusIO_Register.cpp
index 1f88d9e..f802525 100644
--- a/Adafruit_BusIO_Register.cpp
+++ b/Adafruit_BusIO_Register.cpp
@@ -1,5 +1,8 @@
 #include <Adafruit_BusIO_Register.h>
 
+#if !defined(SPI_INTERFACES_COUNT) ||                                          \
+    (defined(SPI_INTERFACES_COUNT) && (SPI_INTERFACES_COUNT > 0))
+
 /*!
  *    @brief  Create a register we access over an I2C Device (which defines the
  * bus and address)
@@ -358,3 +361,5 @@ void Adafruit_BusIO_Register::setAddress(uint16_t address) {
 void Adafruit_BusIO_Register::setAddressWidth(uint16_t address_width) {
   _addrwidth = address_width;
 }
+
+#endif // SPI exists
diff --git a/Adafruit_BusIO_Register.h b/Adafruit_BusIO_Register.h
index a55cfaf..8454b21 100644
--- a/Adafruit_BusIO_Register.h
+++ b/Adafruit_BusIO_Register.h
@@ -2,6 +2,9 @@
 #include <Adafruit_SPIDevice.h>
 #include <Arduino.h>
 
+#if !defined(SPI_INTERFACES_COUNT) ||                                          \
+    (defined(SPI_INTERFACES_COUNT) && (SPI_INTERFACES_COUNT > 0))
+
 #ifndef Adafruit_BusIO_Register_h
 #define Adafruit_BusIO_Register_h
 
@@ -98,3 +101,5 @@ private:
 };
 
 #endif // BusIO_Register_h
+
+#endif // SPI exists
diff --git a/Adafruit_I2CDevice.cpp b/Adafruit_I2CDevice.cpp
index f94b1ee..91724d6 100644
--- a/Adafruit_I2CDevice.cpp
+++ b/Adafruit_I2CDevice.cpp
@@ -50,8 +50,14 @@ bool Adafruit_I2CDevice::detected(void) {
   // A basic scanner, see if it ACK's
   _wire->beginTransmission(_addr);
   if (_wire->endTransmission() == 0) {
+#ifdef DEBUG_SERIAL
+    DEBUG_SERIAL.println(F("Detected"));
+#endif
     return true;
   }
+#ifdef DEBUG_SERIAL
+  DEBUG_SERIAL.println(F("Not detected"));
+#endif
   return false;
 }
 
@@ -125,7 +131,8 @@ bool Adafruit_I2CDevice::write(const uint8_t *buffer, size_t len, bool stop,
 #endif
 
 #ifdef DEBUG_SERIAL
-  // DEBUG_SERIAL.print("Stop: "); DEBUG_SERIAL.println(stop);
+  DEBUG_SERIAL.print("Stop: ");
+  DEBUG_SERIAL.println(stop);
 #endif
 
   if (_wire->endTransmission(stop) == 0) {
@@ -160,7 +167,12 @@ bool Adafruit_I2CDevice::read(uint8_t *buffer, size_t len, bool stop) {
     return false;
   }
 
+#if defined(TinyWireM_h)
+  size_t recv = _wire->requestFrom((uint8_t)_addr, (uint8_t)len);
+#else
   size_t recv = _wire->requestFrom((uint8_t)_addr, (uint8_t)len, (uint8_t)stop);
+#endif
+
   if (recv != len) {
     // Not enough data available to fulfill our obligation!
 #ifdef DEBUG_SERIAL
@@ -227,10 +239,11 @@ uint8_t Adafruit_I2CDevice::address(void) { return _addr; }
  *    Not necessarily that the speed was achieved!
  */
 bool Adafruit_I2CDevice::setSpeed(uint32_t desiredclk) {
-#if (ARDUINO >= 157) && !defined(ARDUINO_STM32_FEATHER)
+#if (ARDUINO >= 157) && !defined(ARDUINO_STM32_FEATHER) && !defined(TinyWireM_h)
   _wire->setClock(desiredclk);
   return true;
 #else
+  (void)desiredclk;
   return false;
 #endif
 }
diff --git a/Adafruit_SPIDevice.cpp b/Adafruit_SPIDevice.cpp
index 975e31f..44d80ec 100644
--- a/Adafruit_SPIDevice.cpp
+++ b/Adafruit_SPIDevice.cpp
@@ -1,6 +1,9 @@
 #include <Adafruit_SPIDevice.h>
 #include <Arduino.h>
 
+#if !defined(SPI_INTERFACES_COUNT) ||                                          \
+    (defined(SPI_INTERFACES_COUNT) && (SPI_INTERFACES_COUNT > 0))
+
 //#define DEBUG_SERIAL Serial
 
 /*!
@@ -437,3 +440,5 @@ bool Adafruit_SPIDevice::write_then_read(uint8_t *write_buffer,
 
   return true;
 }
+
+#endif // SPI exists
diff --git a/Adafruit_SPIDevice.h b/Adafruit_SPIDevice.h
index 87506ae..3dbddec 100644
--- a/Adafruit_SPIDevice.h
+++ b/Adafruit_SPIDevice.h
@@ -1,3 +1,6 @@
+#if !defined(SPI_INTERFACES_COUNT) ||                                          \
+    (defined(SPI_INTERFACES_COUNT) && (SPI_INTERFACES_COUNT > 0))
+
 #include <SPI.h>
 
 #ifndef Adafruit_SPIDevice_h
@@ -97,3 +100,4 @@ private:
 };
 
 #endif // Adafruit_SPIDevice_h
+#endif // has SPI defined
diff --git a/examples/i2corspi_register/i2corspi_register.ino b/examples/i2corspi_register/i2corspi_register.ino
index 555cf3b..992a2e0 100644
--- a/examples/i2corspi_register/i2corspi_register.ino
+++ b/examples/i2corspi_register/i2corspi_register.ino
@@ -28,11 +28,11 @@ void setup() {
   }
 
   Adafruit_BusIO_Register id_reg = Adafruit_BusIO_Register(i2c_dev, spi_dev, ADDRBIT8_HIGH_TOREAD, 0x0F);
-  uint8_t id;
+  uint8_t id=0;
   id_reg.read(&id);
   Serial.print("ID register = 0x"); Serial.println(id, HEX);
 }
 
 void loop() {
   
-}
\ No newline at end of file
+}
diff --git a/examples/spi_registers/spi_registers.ino b/examples/spi_registers/spi_registers.ino
index e24f1aa..091a353 100644
--- a/examples/spi_registers/spi_registers.ino
+++ b/examples/spi_registers/spi_registers.ino
@@ -15,12 +15,12 @@ void setup() {
   }
 
   Adafruit_BusIO_Register id_reg = Adafruit_BusIO_Register(&spi_dev, 0x0F, ADDRBIT8_HIGH_TOREAD);
-  uint8_t id;
+  uint8_t id = 0;
   id_reg.read(&id);
   Serial.print("ID register = 0x"); Serial.println(id, HEX);
 
   Adafruit_BusIO_Register thresh_reg = Adafruit_BusIO_Register(&spi_dev, 0x0C, ADDRBIT8_HIGH_TOREAD, 2, LSBFIRST);
-  uint16_t thresh;
+  uint16_t thresh = 0;
   thresh_reg.read(&thresh);
   Serial.print("Initial threshold register = 0x"); Serial.println(thresh, HEX);
 
@@ -31,4 +31,4 @@ void setup() {
 
 void loop() {
   
-}
\ No newline at end of file
+}