diff --git a/src/saveload/saveload.h b/src/saveload/saveload.h
--- a/src/saveload/saveload.h
+++ b/src/saveload/saveload.h
@@ -716,7 +716,7 @@ struct SaveLoadCompat {
  * @param type VarType holding information about the variable-type
  * @return the SLE_VAR_* part of a variable-type description
  */
-static inline constexpr VarType GetVarMemType(VarType type)
+inline constexpr VarType GetVarMemType(VarType type)
 {
 	return GB(type, 4, 4) << 4;
 }
@@ -727,7 +727,7 @@ static inline constexpr VarType GetVarMe
  * @param type VarType holding information about the file-type
  * @return the SLE_FILE_* part of a variable-type description
  */
-static inline constexpr VarType GetVarFileType(VarType type)
+inline constexpr VarType GetVarFileType(VarType type)
 {
 	return GB(type, 0, 4);
 }
@@ -737,7 +737,7 @@ static inline constexpr VarType GetVarFi
  * @param conv the type to check
  * @return True if it's a numeric type.
  */
-static inline constexpr bool IsNumericType(VarType conv)
+inline constexpr bool IsNumericType(VarType conv)
 {
 	return GetVarMemType(conv) <= SLE_VAR_U64;
 }
@@ -747,7 +747,7 @@ static inline constexpr bool IsNumericTy
  * @param type VarType to get size of.
  * @return size of type in bytes.
  */
-static inline constexpr size_t SlVarSize(VarType type)
+inline constexpr size_t SlVarSize(VarType type)
 {
 	switch (GetVarMemType(type)) {
 		case SLE_VAR_BL: return sizeof(bool);
@@ -775,7 +775,7 @@ static inline constexpr size_t SlVarSize
  * @param size Actual size of variable.
  * @return true iff the sizes match.
  */
-static inline constexpr bool SlCheckVarSize(SaveLoadType cmd, VarType type, size_t length, size_t size)
+inline constexpr bool SlCheckVarSize(SaveLoadType cmd, VarType type, size_t length, size_t size)
 {
 	switch (cmd) {
 		case SL_VAR: return SlVarSize(type) == size;
@@ -1191,7 +1191,7 @@ static inline constexpr bool SlCheckVarS
  * @param minor Minor number of the version to check against. If \a minor is 0 or not specified, only the major number is checked.
  * @return Savegame version is earlier than the specified version.
  */
-static inline bool IsSavegameVersionBefore(SaveLoadVersion major, byte minor = 0)
+inline bool IsSavegameVersionBefore(SaveLoadVersion major, byte minor = 0)
 {
 	extern SaveLoadVersion _sl_version;
 	extern byte            _sl_minor_version;
@@ -1205,7 +1205,7 @@ static inline bool IsSavegameVersionBefo
  * @param major Major number of the version to check against.
  * @return Savegame version is at most the specified version.
  */
-static inline bool IsSavegameVersionBeforeOrAt(SaveLoadVersion major)
+inline bool IsSavegameVersionBeforeOrAt(SaveLoadVersion major)
 {
 	extern SaveLoadVersion _sl_version;
 	return _sl_version <= major;
@@ -1218,7 +1218,7 @@ static inline bool IsSavegameVersionBefo
  * @param version_to   Exclusive savegame version upper bound. SL_MAX_VERSION if no upper bound.
  * @return Active savegame version falls within the given range.
  */
-static inline bool SlIsObjectCurrentlyValid(SaveLoadVersion version_from, SaveLoadVersion version_to)
+inline bool SlIsObjectCurrentlyValid(SaveLoadVersion version_from, SaveLoadVersion version_to)
 {
 	extern const SaveLoadVersion SAVEGAME_VERSION;
 	return version_from <= SAVEGAME_VERSION && SAVEGAME_VERSION < version_to;
@@ -1229,7 +1229,7 @@ static inline bool SlIsObjectCurrentlyVa
  * everything else has a callback function that returns the address based
  * on the saveload data and the current object for non-globals.
  */
-static inline void *GetVariableAddress(const void *object, const SaveLoad &sld)
+inline void *GetVariableAddress(const void *object, const SaveLoad &sld)
 {
 	/* Entry is a null-variable, mostly used to read old savegames etc. */
 	if (GetVarMemType(sld.conv) == SLE_VAR_NULL) {
@@ -1273,7 +1273,7 @@ bool SaveloadCrashWithMissingNewGRFs();
  * anything with them, discarding them in effect
  * @param length The amount of bytes that is being treated this way
  */
-static inline void SlSkipBytes(size_t length)
+inline void SlSkipBytes(size_t length)
 {
 	for (; length != 0; length--) SlReadByte();
 }