diff --git a/src/Val.cc b/src/Val.cc
index 10f7206c82..5f39fbba9a 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -3269,8 +3269,11 @@ bool VectorVal::Assign(unsigned int index, ValPtr element)
 	if ( ! CheckElementType(element) )
 		return false;
 
-	if ( index >= vector_val->size() )
+	auto n = vector_val->size();
+
+	if ( index >= n )
 		{
+		AddHoles(index - n);
 		vector_val->resize(index + 1);
 		if ( yield_types )
 			yield_types->resize(index + 1);
@@ -3314,14 +3317,14 @@ bool VectorVal::Insert(unsigned int index, ValPtr element)
 	vector<ZVal>::iterator it;
 	vector<TypePtr>::iterator types_it;
 
-	const auto& t = element->GetType();
+	auto n = vector_val->size();
 
-	if ( index < vector_val->size() )
-		{
+	if ( index < n )
+		{ // May need to delete previous element
 		it = std::next(vector_val->begin(), index);
 		if ( yield_types )
 			{
-			DeleteIfManaged(*it, t);
+			DeleteIfManaged(*it, element->GetType());
 			types_it = std::next(yield_types->begin(), index);
 			}
 		else if ( managed_yield )
@@ -3332,10 +3335,12 @@ bool VectorVal::Insert(unsigned int index, ValPtr element)
 		it = vector_val->end();
 		if ( yield_types )
 			types_it = yield_types->end();
+		AddHoles(index - n);
 		}
 
 	if ( yield_types )
 		{
+		const auto& t = element->GetType();
 		yield_types->insert(types_it, t);
 		vector_val->insert(it, ZVal(std::move(element), t));
 		}
@@ -3346,6 +3351,16 @@ bool VectorVal::Insert(unsigned int index, ValPtr element)
 	return true;
 	}
 
+void VectorVal::AddHoles(int nholes)
+	{
+	TypePtr fill_t = yield_type;
+	if ( yield_type->Tag() == TYPE_VOID )
+		fill_t = base_type(TYPE_ANY);
+
+	for ( auto i = 0; i < nholes; ++i )
+		vector_val->emplace_back(ZVal(fill_t));
+	}
+
 bool VectorVal::Remove(unsigned int index)
 	{
 	if ( index >= vector_val->size() )
diff --git a/src/Val.h b/src/Val.h
index d5665d1dca..70961d0f59 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -1571,6 +1571,9 @@ private:
 	// element type-checked.
 	bool CheckElementType(const ValPtr& element);
 
+	// Add the given number of "holes" to the end of a vector.
+	void AddHoles(int nholes);
+
 	std::vector<ZVal>* vector_val;
 
 	// For homogeneous vectors (the usual case), the type of the
diff --git a/src/ZVal.cc b/src/ZVal.cc
index 17f94ef825..5480ae0da6 100644
--- a/src/ZVal.cc
+++ b/src/ZVal.cc
@@ -139,6 +139,86 @@ ZVal::ZVal(ValPtr v, const TypePtr& t)
 	}
 	}
 
+ZVal::ZVal(const TypePtr& t)
+	{
+	switch ( t->Tag() ) {
+	case TYPE_BOOL:
+	case TYPE_INT:
+	case TYPE_ENUM:
+		int_val = 0;
+		break;
+
+	case TYPE_COUNT:
+	case TYPE_PORT:
+		uint_val = 0;
+		break;
+
+	case TYPE_DOUBLE:
+	case TYPE_INTERVAL:
+	case TYPE_TIME:
+		double_val = 0.0;
+		break;
+
+	case TYPE_FUNC:
+		func_val = nullptr;
+		break;
+
+	case TYPE_FILE:
+		file_val = nullptr;
+		break;
+
+	case TYPE_LIST:
+		list_val = nullptr;
+		break;
+
+	case TYPE_OPAQUE:
+		opaque_val = nullptr;
+		break;
+
+	case TYPE_PATTERN:
+		re_val = nullptr;
+		break;
+
+	case TYPE_TABLE:
+		table_val = nullptr;
+		break;
+
+	case TYPE_VECTOR:
+		vector_val = nullptr;
+		break;
+
+	case TYPE_RECORD:
+		record_val = nullptr;
+		break;
+
+	case TYPE_STRING:
+		string_val = nullptr;
+		break;
+
+	case TYPE_ADDR:
+		addr_val = nullptr;
+		break;
+
+	case TYPE_SUBNET:
+		subnet_val = nullptr;
+		break;
+
+	case TYPE_ANY:
+		any_val = nullptr;
+		break;
+
+	case TYPE_TYPE:
+		type_val = nullptr;
+		break;
+
+	case TYPE_ERROR:
+	case TYPE_TIMER:
+	case TYPE_UNION:
+	case TYPE_VOID:
+		reporter->InternalError("bad type in ZVal constructor");
+	}
+	}
+
 ValPtr ZVal::ToVal(const TypePtr& t) const
 	{
 	Val* v;
diff --git a/src/ZVal.h b/src/ZVal.h
index b05eb48ce6..f448e3ceef 100644
--- a/src/ZVal.h
+++ b/src/ZVal.h
@@ -43,6 +43,9 @@ union ZVal {
 	// Construct from a given higher-level script value with a given type.
 	ZVal(ValPtr v, const TypePtr& t);
 
+	// Construct an empty value compatible with the given type.
+	ZVal(const TypePtr& t);
+
 	// Convert to a higher-level script value.  The caller needs to
 	// ensure that they're providing the correct type.
 	ValPtr ToVal(const TypePtr& t) const;