diff --git a/include/SFML/Audio/SoundFileFactory.hpp b/include/SFML/Audio/SoundFileFactory.hpp
index 92797f967..61c8cfac3 100644
--- a/include/SFML/Audio/SoundFileFactory.hpp
+++ b/include/SFML/Audio/SoundFileFactory.hpp
@@ -152,8 +152,8 @@ private:
     // Static member data
     ////////////////////////////////////////////////////////////
     // NOLINTBEGIN(readability-identifier-naming)
-    static ReaderFactoryArray s_readers; //!< List of all registered readers
-    static WriterFactoryArray s_writers; //!< List of all registered writers
+    static inline ReaderFactoryArray s_readers; //!< List of all registered readers
+    static inline WriterFactoryArray s_writers; //!< List of all registered writers
     // NOLINTEND(readability-identifier-naming)
 };
 
diff --git a/include/SFML/System/String.hpp b/include/SFML/System/String.hpp
index 9e2449396..c571f5d74 100644
--- a/include/SFML/System/String.hpp
+++ b/include/SFML/System/String.hpp
@@ -58,7 +58,7 @@ public:
     ////////////////////////////////////////////////////////////
     // NOLINTBEGIN(readability-identifier-naming)
     /// Represents an invalid position in the string
-    static const std::size_t InvalidPos{std::u32string::npos};
+    static inline const std::size_t InvalidPos{std::u32string::npos};
     // NOLINTEND(readability-identifier-naming)
 
     ////////////////////////////////////////////////////////////
diff --git a/src/SFML/Audio/SoundFileFactory.cpp b/src/SFML/Audio/SoundFileFactory.cpp
index 592cc4526..a9d147800 100644
--- a/src/SFML/Audio/SoundFileFactory.cpp
+++ b/src/SFML/Audio/SoundFileFactory.cpp
@@ -64,10 +64,6 @@ void ensureDefaultReadersWritersRegistered()
 
 namespace sf
 {
-SoundFileFactory::ReaderFactoryArray SoundFileFactory::s_readers;
-SoundFileFactory::WriterFactoryArray SoundFileFactory::s_writers;
-
-
 ////////////////////////////////////////////////////////////
 std::unique_ptr<SoundFileReader> SoundFileFactory::createReaderFromFilename(const std::filesystem::path& filename)
 {
diff --git a/src/SFML/System/String.cpp b/src/SFML/System/String.cpp
index 7de8eea6f..f25635803 100644
--- a/src/SFML/System/String.cpp
+++ b/src/SFML/System/String.cpp
@@ -37,10 +37,6 @@
 
 namespace sf
 {
-////////////////////////////////////////////////////////////
-const std::size_t String::InvalidPos;
-
-
 ////////////////////////////////////////////////////////////
 String::String() = default;