diff --git a/src/Expr.cc b/src/Expr.cc
index 996a36625e..3c9be75bf9 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -3119,12 +3119,40 @@ void IndexExpr::Assign(Frame* f, Val* v, Opcode op)
 	switch ( v1->Type()->Tag() ) {
 	case TYPE_VECTOR:
 		if ( ! v1->AsVectorVal()->Assign(v2, v, op) )
-			Internal("assignment failed");
+			{
+			if ( v )
+				{
+				ODesc d;
+				v->Describe(&d);
+				auto vt = v->Type();
+				auto vtt = vt->Tag();
+				std::string tn = vtt == TYPE_RECORD ? vt->GetName() : type_name(vtt);
+				Internal(fmt(
+				  "vector index assignment failed for invalid type '%s', value: %s",
+				  tn.data(), d.Description()));
+				}
+			else
+				Internal("assignment failed with null value");
+			}
 		break;
 
 	case TYPE_TABLE:
 		if ( ! v1->AsTableVal()->Assign(v2, v, op) )
-			Internal("assignment failed");
+			{
+			if ( v )
+				{
+				ODesc d;
+				v->Describe(&d);
+				auto vt = v->Type();
+				auto vtt = vt->Tag();
+				std::string tn = vtt == TYPE_RECORD ? vt->GetName() : type_name(vtt);
+				Internal(fmt(
+				  "table index assignment failed for invalid type '%s', value: %s",
+				  tn.data(), d.Description()));
+				}
+			else
+				Internal("assignment failed with null value");
+			}
 		break;
 
 	case TYPE_STRING:
diff --git a/testing/btest/Baseline/language.index-assignment-invalid/out b/testing/btest/Baseline/language.index-assignment-invalid/out
new file mode 100644
index 0000000000..879e1b8fb7
--- /dev/null
+++ b/testing/btest/Baseline/language.index-assignment-invalid/out
@@ -0,0 +1 @@
+internal error in /Users/jon/projects/bro/bro/scripts/base/utils/queue.bro, line 152: vector index assignment failed for invalid type 'myrec', value: [a=T, b=hi, c=<uninitialized>] (Queue::ret[Queue::j])
diff --git a/testing/btest/language/index-assignment-invalid.bro b/testing/btest/language/index-assignment-invalid.bro
new file mode 100644
index 0000000000..6425ca5b1a
--- /dev/null
+++ b/testing/btest/language/index-assignment-invalid.bro
@@ -0,0 +1,31 @@
+# @TEST-EXEC-FAIL: bro -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+@load base/utils/queue
+
+global q: Queue::Queue = Queue::init();
+
+type myrec: record {
+	a: bool &default=T;
+	b: string &default="hi";
+	c: string &optional;
+};
+
+function foo(mr: myrec)
+	{
+	print mr$a;
+	print mr$c;
+	print mr$b;
+	}
+
+event bro_init()
+	{
+	Queue::put(q, "hello");
+	Queue::put(q, "goodbye");
+	Queue::put(q, "test");
+	Queue::put(q, myrec());
+
+	local rval: vector of string = vector();
+	Queue::get_vector(q, rval);
+	print rval;
+	}