diff --git a/WiegandNG.cpp b/WiegandNG.cpp
index 8a6692c..b14ab4a 100644
--- a/WiegandNG.cpp
+++ b/WiegandNG.cpp
@@ -1,4 +1,9 @@
 #include <WiegandNG.h>
+#if defined(ESP8266)
+    #define INTERRUPT_ATTR ICACHE_RAM_ATTR
+#else
+    #define INTERRUPT_ATTR
+#endif
 
 // pcintbranch
 
@@ -86,13 +91,13 @@ bool WiegandNG::available() {
 	return ret;
 }
 
-void WiegandNG::ReadD0 () {
+INTERRUPT_ATTR void WiegandNG::ReadD0 () {
 	_bitCounted++;									// increment bit count for Interrupt connected to D0
 	shift_left(_buffer,_bufferSize,1);				// shift 0 into buffer
 	_lastPulseTime = millis();						// keep track of time last wiegand bit received
 }
 
-void WiegandNG::ReadD1() {
+INTERRUPT_ATTR void WiegandNG::ReadD1() {
 	_bitCounted++;									// increment bit count for Interrupt connected to D1
 	if (_bitCounted > (_bufferSize * 8)) {
 		_bitCounted=0;								// overflowed,