diff --git a/src/serialize.h b/src/serialize.h
index 9420d63..d4a2f74 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -406,7 +406,7 @@ unsigned int GetSerializeSize_impl(const std::vector<T, A>& v, int nType, int nV
 template<typename T, typename A>
 inline unsigned int GetSerializeSize(const std::vector<T, A>& v, int nType, int nVersion)
 {
-    return GetSerializeSize_impl(v, nType, nVersion, std::is_fundamental_v<T>);
+    return GetSerializeSize_impl(v, nType, nVersion, std::is_fundamental<T>{});
 }
 
 
@@ -429,7 +429,7 @@ void Serialize_impl(Stream& os, const std::vector<T, A>& v, int nType, int nVers
 template<typename Stream, typename T, typename A>
 inline void Serialize(Stream& os, const std::vector<T, A>& v, int nType, int nVersion)
 {
-    Serialize_impl(os, v, nType, nVersion, std::is_fundamental_v<T>);
+    Serialize_impl(os, v, nType, nVersion, std::is_fundamental<T>{});
 }
 
 
@@ -470,7 +470,7 @@ void Unserialize_impl(Stream& is, std::vector<T, A>& v, int nType, int nVersion,
 template<typename Stream, typename T, typename A>
 inline void Unserialize(Stream& is, std::vector<T, A>& v, int nType, int nVersion)
 {
-    Unserialize_impl(is, v, nType, nVersion, std::is_fundamental_v<T>);
+    Unserialize_impl(is, v, nType, nVersion, std::is_fundamental<T>{});
 }
 
 
diff --git a/src/util.h b/src/util.h
index c7bbe01..5a70338 100644
--- a/src/util.h
+++ b/src/util.h
@@ -405,10 +405,10 @@ inline std::string DateTimeStrFormat(const char* pszFormat, int64_t nTime)
     return pszTime;
 }
 
-constexpr std::string_view strTimestampFormat = "%Y-%m-%d %H:%M:%S UTC";
+constexpr const char strTimestampFormat[] = "%Y-%m-%d %H:%M:%S UTC";
 inline std::string DateTimeStrFormat(int64_t nTime)
 {
-    return DateTimeStrFormat(strTimestampFormat.c_str(), nTime);
+    return DateTimeStrFormat(strTimestampFormat, nTime);
 }