diff --git a/AK/StringUtils.cpp b/AK/StringUtils.cpp
index 239b3156d08..e808d7d499b 100644
--- a/AK/StringUtils.cpp
+++ b/AK/StringUtils.cpp
@@ -170,6 +170,8 @@ template Optional<u8> convert_to_uint(const StringView& str);
 template Optional<u16> convert_to_uint(const StringView& str);
 template Optional<u32> convert_to_uint(const StringView& str);
 template Optional<u64> convert_to_uint(const StringView& str);
+template Optional<long> convert_to_uint(const StringView& str);
+template Optional<long long> convert_to_uint(const StringView& str);
 
 template<typename T>
 Optional<T> convert_to_uint_from_hex(const StringView& str)
diff --git a/AK/StringView.cpp b/AK/StringView.cpp
index f1ee2dbb869..82c7b946197 100644
--- a/AK/StringView.cpp
+++ b/AK/StringView.cpp
@@ -243,6 +243,8 @@ template Optional<u8> StringView::to_uint() const;
 template Optional<u16> StringView::to_uint() const;
 template Optional<u32> StringView::to_uint() const;
 template Optional<u64> StringView::to_uint() const;
+template Optional<long> StringView::to_uint() const;
+template Optional<long long> StringView::to_uint() const;
 
 unsigned StringView::hash() const
 {