diff --git a/cores/esp8266/core_esp8266_waveform.cpp b/cores/esp8266/core_esp8266_waveform.cpp
index bd9667cf72..597a8e88ab 100644
--- a/cores/esp8266/core_esp8266_waveform.cpp
+++ b/cores/esp8266/core_esp8266_waveform.cpp
@@ -178,17 +178,15 @@ int ICACHE_RAM_ATTR stopWaveform(uint8_t pin) {
   }
   // If user sends in a pin >16 but <32, this will always point to a 0 bit
   // If they send >=32, then the shift will result in 0 and it will also return false
-  uint32_t mask = 1<<pin;
-  if (!(waveformEnabled & mask)) {
-    return false; // It's not running, nothing to do here
-  }
-  waveformToDisable |= mask;
-  // Ensure timely service....
-  if (T1L > microsecondsToClockCycles(10)) {
-    timer1_write(microsecondsToClockCycles(10));
-  }
-  while (waveformToDisable) {
-    /* no-op */ // Can't delay() since stopWaveform may be called from an IRQ
+  if (waveformEnabled & (1UL << pin)) {
+    waveformToDisable = 1UL << pin;
+    // Must not interfere if Timer is due shortly
+    if (T1L > microsecondsToClockCycles(10)) {
+      timer1_write(microsecondsToClockCycles(10));
+    }
+    while (waveformToDisable) {
+      /* no-op */ // Can't delay() since stopWaveform may be called from an IRQ
+    }
   }
   if (!waveformEnabled && !timer1CB) {
     deinitTimer();