diff --git a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
index 1b38a9807b..79017c6d46 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp
@@ -344,7 +344,7 @@ int currency_digits(StringView currency)
 }
 
 // 15.5.3 FormatNumericToString ( intlObject, x ), https://tc39.es/ecma402/#sec-formatnumberstring
-FormatResult format_numeric_to_string(GlobalObject& global_object, NumberFormatBase& intl_object, Value number)
+FormatResult format_numeric_to_string(GlobalObject& global_object, NumberFormatBase const& intl_object, Value number)
 {
     // 1. If ℝ(x) < 0 or x is -0𝔽, let isNegative be true; else let isNegative be false.
     bool is_negative = is_less_than(number, 0) || number.is_negative_zero();
diff --git a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.h b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.h
index 171a24455c..ba36285086 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.h
+++ b/Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.h
@@ -221,7 +221,7 @@ struct RawFormatResult : public FormatResult {
 };
 
 int currency_digits(StringView currency);
-FormatResult format_numeric_to_string(GlobalObject& global_object, NumberFormatBase& intl_object, Value number);
+FormatResult format_numeric_to_string(GlobalObject& global_object, NumberFormatBase const& intl_object, Value number);
 Vector<PatternPartition> partition_number_pattern(GlobalObject& global_object, NumberFormat& number_format, Value number);
 Vector<PatternPartition> partition_notation_sub_pattern(GlobalObject& global_object, NumberFormat& number_format, Value number, String formatted_string, int exponent);
 String format_numeric(GlobalObject& global_object, NumberFormat& number_format, Value number);