diff --git a/src/crc32.cpp b/src/crc32.cpp
index 535f20a..f8962bb 100644
--- a/src/crc32.cpp
+++ b/src/crc32.cpp
@@ -76,17 +76,19 @@ namespace wren {
 #endif
 	} //unnamed namespace
 
-	[[gnu::const]]
-	std::uint32_t runtime_crc32c (const char* data, std::size_t size, std::uint32_t crc) {
+	namespace detail {
+		[[gnu::const]]
+		std::uint32_t runtime_crc32c (const char* data, std::size_t size, std::uint32_t crc) {
 #if defined(WRENPP_WITH_SSE42)
-		//if (_may_i_use_cpu_feature(_FEATURE_SSE4_2)) {
-		if (__builtin_cpu_supports("sse4.2")) {
-			return crc32c_hw(data, size, crc);
-		}
-		else
+			//if (_may_i_use_cpu_feature(_FEATURE_SSE4_2)) {
+			if (__builtin_cpu_supports("sse4.2")) {
+				return crc32c_hw(data, size, crc);
+			}
+			else
 #endif
-		{
-			return detail::crc32<detail::g_castagnoli_polynomial>(data, size, crc);
+			{
+				return detail::crc32<detail::g_castagnoli_polynomial>(data, size, crc);
+			}
 		}
-	}
+	} //namespace detail
 } //namespace wren