diff --git a/src/is_na.cpp b/src/is_na.cpp
index 74a9f6e..a976d39 100644
--- a/src/is_na.cpp
+++ b/src/is_na.cpp
@@ -9,7 +9,7 @@
 namespace duckdb {
 namespace rfuns {
 
-void isna_double_loop(idx_t count, const double* data, bool* result_data, ValidityMask mask) {
+void isna_double_loop_flat(idx_t count, const double* data, bool* result_data, ValidityMask mask) {
 	idx_t base_idx = 0;
 	auto entry_count = ValidityMask::EntryCount(count);
 	for (idx_t entry_idx = 0; entry_idx < entry_count; entry_idx++) {
@@ -41,6 +41,24 @@ void isna_double_loop(idx_t count, const double* data, bool* result_data, Validi
 	}
 }
 
+void isna_double_loop_unified(idx_t count, const double* data, bool* result_data, const SelectionVector* sel, ValidityMask mask) {
+	if (!mask.AllValid()) {
+		for (idx_t i = 0; i < count; i++) {
+			auto idx = sel->get_index(i);
+			if (mask.RowIsValidUnsafe(idx)) {
+				result_data[i] = std::isnan(data[idx]);
+			} else {
+				result_data[i] = true;
+			}
+		}
+	} else {
+		for (idx_t i = 0; i < count; i++) {
+			auto idx = sel->get_index(i);
+			result_data[i] = std::isnan(data[idx]);
+		}
+	}
+}
+
 void isna_double(DataChunk &args, ExpressionState &state, Vector &result) {
 	auto count = args.size();
 	auto input = args.data[0];
@@ -49,7 +67,7 @@ void isna_double(DataChunk &args, ExpressionState &state, Vector &result) {
 		case VectorType::FLAT_VECTOR: {
 			result.SetVectorType(VectorType::FLAT_VECTOR);
 
-			isna_double_loop(
+			isna_double_loop_flat(
 				count,
 				FlatVector::GetData<double>(input),
 				FlatVector::GetData<bool>(result),
@@ -60,7 +78,7 @@ void isna_double(DataChunk &args, ExpressionState &state, Vector &result) {
 		}
 
 		case VectorType::CONSTANT_VECTOR: {
-			result.SetVectorType(VectorType::CONSTANT_VECTOR);
+			result.SetVectorType(VectorType::FLAT_VECTOR);
 			auto result_data = ConstantVector::GetData<bool>(result);
 			auto ldata = ConstantVector::GetData<double>(input);
 
@@ -74,10 +92,11 @@ void isna_double(DataChunk &args, ExpressionState &state, Vector &result) {
 			input.ToUnifiedFormat(count, vdata);
 			result.SetVectorType(VectorType::FLAT_VECTOR);
 
-			isna_double_loop(
+			isna_double_loop_unified(
 				count,
 				UnifiedVectorFormat::GetData<double>(vdata),
 				FlatVector::GetData<bool>(result),
+				vdata.sel,
 				vdata.validity
 			);
 
@@ -86,7 +105,7 @@ void isna_double(DataChunk &args, ExpressionState &state, Vector &result) {
 	}
 }
 
-void isna_any_loop(idx_t count, bool* result_data, ValidityMask mask) {
+void isna_any_loop_flat(idx_t count, bool* result_data, ValidityMask mask) {
 	if (mask.AllValid()) {
 		for (idx_t i = 0; i < count; i++) {
 			result_data[i] = false;
@@ -121,6 +140,23 @@ void isna_any_loop(idx_t count, bool* result_data, ValidityMask mask) {
 
 }
 
+void isna_any_loop_unified(idx_t count, bool* result_data, const SelectionVector* sel, ValidityMask mask) {
+	if (!mask.AllValid()) {
+		for (idx_t i = 0; i < count; i++) {
+			auto idx = sel->get_index(i);
+			if (mask.RowIsValidUnsafe(idx)) {
+				result_data[i] = false;
+			} else {
+				result_data[i] = true;
+			}
+		}
+	} else {
+		for (idx_t i = 0; i < count; i++) {
+			result_data[i] = true;
+		}
+	}
+}
+
 void isna_any(DataChunk &args, ExpressionState &state, Vector &result) {
 	auto count = args.size();
 	auto input = args.data[0];
@@ -128,7 +164,7 @@ void isna_any(DataChunk &args, ExpressionState &state, Vector &result) {
 	switch(input.GetVectorType()) {
 		case VectorType::FLAT_VECTOR: {
 			result.SetVectorType(VectorType::FLAT_VECTOR);
-			isna_any_loop(
+			isna_any_loop_flat(
 				count,
 				FlatVector::GetData<bool>(result),
 				FlatVector::Validity(input)
@@ -149,9 +185,10 @@ void isna_any(DataChunk &args, ExpressionState &state, Vector &result) {
 			UnifiedVectorFormat vdata;
 			input.ToUnifiedFormat(count, vdata);
 			result.SetVectorType(VectorType::FLAT_VECTOR);
-			isna_any_loop(
+			isna_any_loop_unified(
 				count,
 				FlatVector::GetData<bool>(result),
+				vdata.sel,
 				vdata.validity
 			);
 
@@ -165,8 +202,13 @@ void isna_any(DataChunk &args, ExpressionState &state, Vector &result) {
 ScalarFunctionSet base_r_is_na() {
 	ScalarFunctionSet set("r_base::is.na");
 
-	set.AddFunction(ScalarFunction({LogicalType::DOUBLE}, LogicalType::BOOLEAN, isna_double));
-	set.AddFunction(ScalarFunction({LogicalType::ANY}   , LogicalType::BOOLEAN, isna_any));
+	ScalarFunction is_na_double({LogicalType::DOUBLE}, LogicalType::BOOLEAN, isna_double);
+	is_na_double.null_handling = FunctionNullHandling::SPECIAL_HANDLING;
+	set.AddFunction(is_na_double);
+
+	ScalarFunction is_na_any({LogicalType::ANY}   , LogicalType::BOOLEAN, isna_any);
+	is_na_any.null_handling = FunctionNullHandling::SPECIAL_HANDLING;
+	set.AddFunction(is_na_any);
 
 	return set;
 }