diff --git a/tests/data/Calculation/LookupRef/HLOOKUP.php b/tests/data/Calculation/LookupRef/HLOOKUP.php
index bc52e707..26601721 100644
--- a/tests/data/Calculation/LookupRef/HLOOKUP.php
+++ b/tests/data/Calculation/LookupRef/HLOOKUP.php
@@ -1,6 +1,6 @@
 <?php
 
-function orderGrid()
+function orderGrid(): array
 {
     return [
         ['Order ID', 10247, 10249, 10250, 10251, 10252, 10253],
@@ -9,7 +9,7 @@ function orderGrid()
     ];
 }
 
-function partsGrid()
+function partsGrid(): array
 {
     return [
         ['Axles', 'Bearings', 'Bolts'],
diff --git a/tests/data/Calculation/LookupRef/VLOOKUP.php b/tests/data/Calculation/LookupRef/VLOOKUP.php
index eb1b142f..ac60bda3 100644
--- a/tests/data/Calculation/LookupRef/VLOOKUP.php
+++ b/tests/data/Calculation/LookupRef/VLOOKUP.php
@@ -1,6 +1,6 @@
 <?php
 
-function densityGrid()
+function densityGrid(): array
 {
     return [
         ['Density', 'Viscosity', 'Temperature'],