diff --git a/CHANGES b/CHANGES
index aeb76687b5..b5e3e870b0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+3818.	[bug]		Stop lying to the optimizer that 'void *arg' is a
+			constant in isc_event_allocate.
+
 3815.	[doc]		Clarify "nsupdate -y" usage in man page. [RT #35808]
 
 3809.	[doc]		Fix NSID documentation.
diff --git a/lib/isc/event.c b/lib/isc/event.c
index 8ab75240dc..2f08277939 100644
--- a/lib/isc/event.c
+++ b/lib/isc/event.c
@@ -41,7 +41,26 @@ destroy(isc_event_t *event) {
 
 isc_event_t *
 isc_event_allocate(isc_mem_t *mctx, void *sender, isc_eventtype_t type,
-		   isc_taskaction_t action, const void *arg, size_t size)
+		   isc_taskaction_t action, void *arg, size_t size)
+{
+	isc_event_t *event;
+
+	REQUIRE(size >= sizeof(struct isc_event));
+	REQUIRE(action != NULL);
+
+	event = isc_mem_get(mctx, size);
+	if (event == NULL)
+		return (NULL);
+
+	ISC_EVENT_INIT(event, size, 0, NULL, type, action, arg,
+		       sender, destroy, mctx);
+
+	return (event);
+}
+
+isc_event_t *
+isc_event_constallocate(isc_mem_t *mctx, void *sender, isc_eventtype_t type,
+		        isc_taskaction_t action, const void *arg, size_t size)
 {
 	isc_event_t *event;
 	void *deconst_arg;
diff --git a/lib/isc/include/isc/event.h b/lib/isc/include/isc/event.h
index 68fabb2fcc..40e01fae40 100644
--- a/lib/isc/include/isc/event.h
+++ b/lib/isc/include/isc/event.h
@@ -90,7 +90,10 @@ ISC_LANG_BEGINDECLS
 
 isc_event_t *
 isc_event_allocate(isc_mem_t *mctx, void *sender, isc_eventtype_t type,
-		   isc_taskaction_t action, const void *arg, size_t size);
+		   isc_taskaction_t action, void *arg, size_t size);
+isc_event_t *
+isc_event_constallocate(isc_mem_t *mctx, void *sender, isc_eventtype_t type,
+		        isc_taskaction_t action, const void *arg, size_t size);
 /*%<
  * Allocate an event structure. 
  *