diff --git a/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupt.ino b/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupt.ino
index b386b1d83f..aae06082eb 100644
--- a/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupt.ino
+++ b/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupt.ino
@@ -1,4 +1,5 @@
 #include <Arduino.h>
+#include <Schedule.h>
 #include "FunctionalInterrupts.h"
 
 #if defined(ESP32)
@@ -16,10 +17,15 @@ class Button {
   public:
     Button(uint8_t reqPin) : PIN(reqPin) {
       pinMode(PIN, INPUT_PULLUP);
-      attachInterrupt(PIN, std::bind(&Button::isr, this), FALLING);
+      // Arduino C API:
+      attachInterruptArg(PIN, [](void* self) { static_cast<Button*>(self)->isr(); }, this, FALLING); // works on ESP32; fails on ESP8266: "ISR not in IRAM"
+      //attachInterruptArg(PIN, reinterpret_cast<void(*)(void*)>(&isr_static), this, FALLING); // works on ESP32; works on ESP8266
+      // FunctionalInterrupts API:
+      //attachInterrupt(PIN, [this]() { isr(); }, FALLING); // works on ESP32; works on ESP8266
+      //attachScheduledInterrupt(PIN, [this](InterruptInfo ii) { Serial.print("Pin "); Serial.println(ii.pin); isr(); }, FALLING); // works on ESP32; works on ESP8266
     };
     ~Button() {
-      detachFunctionalInterrupt(PIN);
+      detachInterrupt(PIN);
     }
 
 #if defined(ESP8266)
@@ -32,6 +38,15 @@ class Button {
       pressed = true;
     }
 
+#if defined(ESP8266)
+    static void ICACHE_RAM_ATTR isr_static(Button* const self)
+#elif defined(ESP32)
+    static void IRAM_ATTR isr_static(Button* const self)
+#endif
+    {
+        self->isr();
+    }
+
     void checkPressed() {
       if (pressed) {
         Serial.printf("Button on pin %u has been pressed %u times\n", PIN, numberKeyPresses);
@@ -41,19 +56,26 @@ class Button {
 
   private:
     const uint8_t PIN;
-    volatile uint32_t numberKeyPresses;
-    volatile bool pressed;
+    volatile uint32_t numberKeyPresses = 0;
+    volatile bool pressed = false;
 };
 
-Button button1(BUTTON1);
-Button button2(BUTTON2);
+Button* button1;
+Button* button2;
 
 
 void setup() {
   Serial.begin(115200);
+  schedule_function([]() { Serial.println("Scheduled function"); });
+  Serial.println("FunctionalInterrupt test/example");
+
+  button1 = new Button(BUTTON1);
+  button2 = new Button(BUTTON2);
+
+  Serial.println("setup() complete");
 }
 
 void loop() {
-  button1.checkPressed();
-  button2.checkPressed();
+  button1->checkPressed();
+  button2->checkPressed();
 }
diff --git a/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupts.cpp b/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupts.cpp
index be29554bc2..1867e7bd92 100644
--- a/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupts.cpp
+++ b/libraries/esp8266/examples/GPIO/FunctionalInterrupt/FunctionalInterrupts.cpp
@@ -33,10 +33,7 @@ void attachInterrupt(uint8_t pin, std::function<void(void)> intRoutine, int mode
 	// use the local interrupt routine which takes the ArgStructure as argument
 
 	void* localArg = detachInterruptArg(pin);
-	if (localArg)
-	{
-		cleanupFunctional(localArg);
-	}
+	if (localArg) cleanupFunctional(localArg);
 
 	FunctionInfo* fi = new FunctionInfo;
 	fi->reqFunction = intRoutine;
@@ -50,10 +47,7 @@ void attachInterrupt(uint8_t pin, std::function<void(void)> intRoutine, int mode
 void attachScheduledInterrupt(uint8_t pin, std::function<void(InterruptInfo)> scheduledIntRoutine, int mode)
 {
 	void* localArg = detachInterruptArg(pin);
-	if (localArg)
-	{
-		cleanupFunctional(localArg);
-	}
+	if (localArg) cleanupFunctional(localArg);
 
 	InterruptInfo* ii = new InterruptInfo(pin);
 
@@ -70,8 +64,5 @@ void attachScheduledInterrupt(uint8_t pin, std::function<void(InterruptInfo)> sc
 void detachFunctionalInterrupt(uint8_t pin)
 {
 	void* localArg = detachInterruptArg(pin);
-	if (localArg)
-	{
-		cleanupFunctional(localArg);
-	}
+	if (localArg) cleanupFunctional(localArg);
 }