diff --git a/speeduino/maths.h b/speeduino/maths.h
index d0bafbea..0dcd7206 100644
--- a/speeduino/maths.h
+++ b/speeduino/maths.h
@@ -144,7 +144,7 @@ static inline uint32_t div100(uint32_t n) {
 #endif
 }
 
-#if defined(__arm__) && !defined(CORE_TEENSY)
+#if defined(__arm__)
 static inline int div100(int n) {
     return DIV_ROUND_CLOSEST(n, 100U, int);
 }
diff --git a/test/test_init/tests_init.cpp b/test/test_init/tests_init.cpp
index e33aee50..0851e103 100644
--- a/test/test_init/tests_init.cpp
+++ b/test/test_init/tests_init.cpp
@@ -246,6 +246,7 @@ void test_initialisation_outputs_reset_control_use_board_default(void)
 
 void test_initialisation_outputs_reset_control_override_board_default(void)
 {
+#if defined(ARDUINO_ARCH_AVR)
   prepareForInitialiseAll(9);
   configPage4.resetControlConfig = RESET_CONTROL_PREVENT_WHEN_RUNNING;
   configPage4.resetControlPin = 45; // Use a different pin
@@ -254,10 +255,12 @@ void test_initialisation_outputs_reset_control_override_board_default(void)
   TEST_ASSERT_EQUAL(45, pinResetControl);  
   TEST_ASSERT_EQUAL(resetControl, RESET_CONTROL_PREVENT_WHEN_RUNNING);
   TEST_ASSERT_EQUAL(OUTPUT, getPinMode(pinResetControl));
+#endif
 }
 
 void test_initialisation_user_pin_override_board_default(void)
 {
+#if defined(ARDUINO_ARCH_AVR)
   prepareForInitialiseAll(3);
   // We do not test all pins, too many & too fragile. So fingers crossed the 
   // same pattern is used for all.
@@ -266,6 +269,7 @@ void test_initialisation_user_pin_override_board_default(void)
 
   TEST_ASSERT_EQUAL(15, pinTachOut);  
   TEST_ASSERT_EQUAL(OUTPUT, getPinMode(pinTachOut));
+#endif
 }
 
 // All config user pin fields are <= 6 *bits*. So too small to
@@ -286,6 +290,7 @@ void test_initialisation_user_pin_not_valid_no_override(void)
 
 void test_initialisation_input_user_pin_does_not_override_outputpin(void)
 {
+#if defined(ARDUINO_ARCH_AVR)
   // A user defineable input pin should not overwrite any output pins.
   prepareForInitialiseAll(3);
   configPage6.launchPin = 49; // 49 is the default tacho output
@@ -294,6 +299,7 @@ void test_initialisation_input_user_pin_does_not_override_outputpin(void)
   TEST_ASSERT_EQUAL(49, pinTachOut);  
   TEST_ASSERT_EQUAL(OUTPUT, getPinMode(pinTachOut));
   TEST_ASSERT_EQUAL(49, pinLaunch);  
+#endif
 }
 
 void testInitialisation()
diff --git a/test/test_math/test_division.cpp b/test/test_math/test_division.cpp
index 4822988c..f4a547e1 100644
--- a/test/test_math/test_division.cpp
+++ b/test/test_math/test_division.cpp
@@ -63,7 +63,7 @@ void test_maths_div100_S16(void)
 void test_maths_div100_S32(void)
 {
   //Check both the signed and unsigned results
-#if defined(__arm__) && !defined(CORE_TEENSY)
+#if defined(__arm__)
   test_div100_Seed<int>(100U);
   test_div100_Seed<int>(10000U);
   test_div100_Seed<int>(100000000UL);
@@ -151,9 +151,12 @@ void test_maths_udiv_32_16_closest(void)
 #endif
 }
 
+#if defined(ARDUINO_ARCH_AVR)
 static uint32_t indexToDividend(int16_t index) {
   return (uint32_t)index  + (UINT16_MAX*index);
 }
+#endif
+
 void test_maths_udiv_32_16_perf(void)
 {
 #if defined(ARDUINO_ARCH_AVR)