diff --git a/src/executor/Executor.cxx b/src/executor/Executor.cxx
index 310e7ce18..3c05ed52e 100644
--- a/src/executor/Executor.cxx
+++ b/src/executor/Executor.cxx
@@ -386,7 +386,13 @@ void ExecutorBase::wait_with_select(long long wait_length)
     fd_set fd_r(selectRead_);
     fd_set fd_w(selectWrite_);
     fd_set fd_x(selectExcept_);
-    if (!empty()) {
+    // We will check the queue for any prior wakeups after this call. If we
+    // already processed the executables, the wakeup is not necessary. Without
+    // this clear, there would always be two select() iterations happening when
+    // we are done with work and can go to sleep.
+    selectHelper_.clear_wakeup();
+    if (!empty())
+    {
         wait_length = 0;
     }
     long long max_sleep = MSEC_TO_NSEC(config_executor_max_sleep_msec());
diff --git a/src/os/OSSelectWakeup.cxx b/src/os/OSSelectWakeup.cxx
index 2ee394bff..d3ed3784f 100644
--- a/src/os/OSSelectWakeup.cxx
+++ b/src/os/OSSelectWakeup.cxx
@@ -55,6 +55,11 @@ int OSSelectWakeup::select(int nfds, fd_set *readfds,
         else
         {
 #if OPENMRN_FEATURE_DEVICE_SELECT
+            // It is important that we do this select_clear() in the same
+            // critical section as checking pendingWakeup above. This ensures
+            // tht all wakeups before this clear cause sleep to be zero, and
+            // all wakeups after this clear will cause the event group bit to
+            // be set.
             Device::select_clear();
 #endif
         }
@@ -189,6 +194,15 @@ void OSSelectWakeup::esp_start_select(fd_set *readfds, fd_set *writefds,
     exceptFds_ = exceptfds;
     exceptFdsOrig_ = *exceptfds;
     FD_ZERO(exceptFds_);
+    if (pendingWakeup_)
+    {
+        // There is a race condition between the Executor deciding to run
+        // select, and the internal implementation of select() calling this
+        // function. Since we only get the semaphone in this call, the wakeup
+        // functions are noops if they hit during this window. If there was a
+        // missed wakeup, we repeat it.
+        esp_wakeup();
+    }
 }
 
 /// This function marks the stored semaphore as invalid which indicates no
@@ -226,7 +240,6 @@ void OSSelectWakeup::esp_wakeup()
 /// call from within an ISR context.
 void OSSelectWakeup::esp_wakeup_from_isr()
 {
-    AtomicHolder h(this);
     BaseType_t woken = pdFALSE;
 
     // If our VFS FD is not set in the except fd_set we can exit early.
diff --git a/src/os/OSSelectWakeup.hxx b/src/os/OSSelectWakeup.hxx
index 57f1ea708..ed45a6adf 100644
--- a/src/os/OSSelectWakeup.hxx
+++ b/src/os/OSSelectWakeup.hxx
@@ -159,6 +159,10 @@ public:
 #if OPENMRN_FEATURE_RTOS_FROM_ISR
     void wakeup_from_isr()
     {
+#if defined(ESP_PLATFORM)
+        // On multi-core ESP32s we need to lock objects even in ISRs.
+        AtomicHolder h(this);
+#endif
         pendingWakeup_ = true;
         if (inSelect_)
         {