diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index c8d7fde..c83c0e0 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -17,10 +17,10 @@
  *  You should have received a copy of the GNU General Public License
  *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
  */
+#include "DCC.h" // includes "Motordriver.h" and <Arduino.h>
 #include "defines.h"
 #include "StringFormatter.h"
 #include "DCCEXParser.h"
-#include "DCC.h"
 #include "DCCWaveform.h"
 #include "Turnouts.h"
 #include "Outputs.h"
diff --git a/DCCTimer.h b/DCCTimer.h
index d421828..0af3614 100644
--- a/DCCTimer.h
+++ b/DCCTimer.h
@@ -37,5 +37,14 @@ class DCCTimer {
   private:
 };
 
+#if defined(ARDUINO_ARCH_ESP32)
 extern portMUX_TYPE timerMux;
 #endif
+
+#if !(defined(ARDUINO_ARCH_ESP32) || defined(ARDUINO_ARCH_ESP8266))
+#ifndef IRAM_ATTR
+#define IRAM_ATTR
+#endif
+#endif
+
+#endif //DCCTimer.h
diff --git a/DCCWaveform.cpp b/DCCWaveform.cpp
index 439e781..a8b83e4 100644
--- a/DCCWaveform.cpp
+++ b/DCCWaveform.cpp
@@ -17,7 +17,7 @@
  *  You should have received a copy of the GNU General Public License
  *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
  */
- #pragma GCC optimize ("-O3")
+#pragma GCC optimize ("-O3")
 #include <Arduino.h>
 
 #include "defines.h"