diff --git a/include/duckhandy/endianness.hpp b/include/duckhandy/endianness.hpp
index 0da8d0c..4e704a9 100644
--- a/include/duckhandy/endianness.hpp
+++ b/include/duckhandy/endianness.hpp
@@ -93,6 +93,28 @@ namespace dhandy {
 		return static_cast<int64_t>(__builtin_bswap64(static_cast<uint64_t>(parV)));
 #else
 #	error "Unsupported endianness"
+#endif
+	}
+	template <>
+	[[gnu::pure]] inline constexpr long long int htobe (long long int parV) {
+		static_assert(sizeof(long long int) == sizeof(uint64_t), "Size mismatch");
+#if __BYTE_ORDER == __BIG_ENDIAN
+		return parV;
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+		return static_cast<long long int>(__builtin_bswap64(static_cast<uint64_t>(parV)));
+#else
+#	error "Unsupported endianness"
+#endif
+	}
+	template <>
+	[[gnu::pure]] inline constexpr unsigned long long int htobe (unsigned long long int parV) {
+		static_assert(sizeof(unsigned long long int) == sizeof(uint64_t), "Size mismatch");
+#if __BYTE_ORDER == __BIG_ENDIAN
+		return parV;
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+		return static_cast<unsigned long long int>(__builtin_bswap64(static_cast<uint64_t>(parV)));
+#else
+#	error "Unsupported endianness"
 #endif
 	}
 
@@ -162,6 +184,28 @@ namespace dhandy {
 		return parV;
 #else
 #	error "Unsupported endianness"
+#endif
+	}
+	template <>
+	[[gnu::pure]] inline constexpr long long int htole (long long int parV) {
+		static_assert(sizeof(long long int) == sizeof(uint64_t), "Size mismatch");
+#if __BYTE_ORDER == __BIG_ENDIAN
+		return static_cast<long long int>(__builtin_bswap64(static_cast<uint64_t>(parV)));
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+		return parV;
+#else
+#	error "Unsupported endianness"
+#endif
+	}
+	template <>
+	[[gnu::pure]] inline constexpr unsigned long long int htole (unsigned long long int parV) {
+		static_assert(sizeof(unsigned long long int) == sizeof(uint64_t), "Size mismatch");
+#if __BYTE_ORDER == __BIG_ENDIAN
+		return static_cast<unsigned long long int>(__builtin_bswap64(static_cast<uint64_t>(parV)));
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+		return parV;
+#else
+#	error "Unsupported endianness"
 #endif
 	}