diff --git a/src/core/ev.c b/src/core/ev.c
index 2917039e..5f999764 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -603,11 +603,19 @@ void janet_addtimeout(double sec) {
 }
 
 void janet_ev_inc_refcount(void) {
-    janet_vm.extra_listeners++;
+#ifdef JANET_WINDOWS
+    InterlockedIncrement(&janet_vm.extra_listeners);
+#else
+    __atomic_add_fetch(&janet_vm.extra_listeners, 1, __ATOMIC_RELAXED);
+#endif
 }
 
 void janet_ev_dec_refcount(void) {
-    janet_vm.extra_listeners--;
+#ifdef JANET_WINDOWS
+    InterlockedDecrement(&janet_vm.extra_listeners);
+#else
+    __atomic_add_fetch(&janet_vm.extra_listeners, -1, __ATOMIC_RELAXED);
+#endif
 }
 
 /* Channels */
diff --git a/src/core/state.h b/src/core/state.h
index b5c270e9..c7b3534b 100644
--- a/src/core/state.h
+++ b/src/core/state.h
@@ -157,7 +157,7 @@ struct JanetVM {
     JanetListenerState **listeners;
     size_t listener_count;
     size_t listener_cap;
-    size_t extra_listeners;
+    volatile size_t extra_listeners; /* used in signal handler, must be volatile */
     JanetTable threaded_abstracts; /* All abstract types that can be shared between threads (used in this thread) */
     JanetTable active_tasks; /* All possibly live task fibers - used just for tracking */
     JanetTable signal_handlers;