diff --git a/src/Func.cc b/src/Func.cc
index e9933a6a6a..791a3b820e 100644
--- a/src/Func.cc
+++ b/src/Func.cc
@@ -449,6 +449,11 @@ void BroFunc::AddBody(IntrusivePtr<Stmt> new_body, id_list* new_inits,
 	if ( new_frame_size > frame_size )
 		frame_size = new_frame_size;
 
+	auto num_args = FType()->Args()->NumFields();
+
+	if ( num_args > static_cast<int>(frame_size) )
+		frame_size = num_args;
+
 	new_body = AddInits(std::move(new_body), new_inits);
 
 	if ( Flavor() == FUNC_FLAVOR_FUNCTION )
diff --git a/testing/btest/Baseline/language.alternate-event-hook-prototypes/out b/testing/btest/Baseline/language.alternate-event-hook-prototypes/out
index 8aad989b3d..aa70ccc747 100644
--- a/testing/btest/Baseline/language.alternate-event-hook-prototypes/out
+++ b/testing/btest/Baseline/language.alternate-event-hook-prototypes/out
@@ -1,4 +1,4 @@
-warning in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes/alternate-event-hook-prototypes.zeek, line 56 and /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes/alternate-event-hook-prototypes.zeek, line 10: use of deprecated prototype (hook(c:count;) : bool and my_hook)
+warning in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes/alternate-event-hook-prototypes.zeek, line 68 and /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.alternate-event-hook-prototypes/alternate-event-hook-prototypes.zeek, line 10: use of deprecated prototype (hook(c:count;) : bool and my_hook)
 my_hook, infinite, 13
 my_hook, 13, infinite
 my_hook, infinite
@@ -9,3 +9,4 @@ my_event, 42, enantiodromia
 my_event, enantiodromia
 my_event, 42
 my_event
+foo, C
diff --git a/testing/btest/language/alternate-event-hook-prototypes.zeek b/testing/btest/language/alternate-event-hook-prototypes.zeek
index e58c542b99..62573479d6 100644
--- a/testing/btest/language/alternate-event-hook-prototypes.zeek
+++ b/testing/btest/language/alternate-event-hook-prototypes.zeek
@@ -13,6 +13,18 @@ global my_hook: hook(s: string);
 global my_hook: hook(c: count) &deprecated;
 global my_hook: hook();
 
+# Required Frame size gets (re)calculated on AddBody, so this "foo" setup is
+# checking that if the only existing body doesn't use all arguments, the Frame
+# size is still allocated sufficiently to hold all arguments of the canonical
+# prototype.
+global foo: event(a: string, b: string, c: string);
+global foo: event(c: string);
+
+event foo(c: string)
+	{
+	print "foo", c;
+	}
+
 event my_event(s: string, c: count)
 	{
 	print "my_event", s, c;
@@ -67,4 +79,5 @@ event zeek_init()
 	{
 	hook my_hook("infinite", 13);
 	event my_event("enantiodromia", 42);
+	event foo("A", "B", "C");
 	}