diff --git a/src/SongFilter.cxx b/src/SongFilter.cxx
index 17dece666..c660870b2 100644
--- a/src/SongFilter.cxx
+++ b/src/SongFilter.cxx
@@ -44,7 +44,11 @@
 #define LOCATE_TAG_FILE_KEY_OLD "filename"
 #define LOCATE_TAG_ANY_KEY      "any"
 
-unsigned
+/**
+ * @return #TAG_NUM_OF_ITEM_TYPES on error
+ */
+gcc_pure
+static unsigned
 locate_parse_type(const char *str) noexcept
 {
 	if (StringEqualsCaseASCII(str, LOCATE_TAG_FILE_KEY) ||
diff --git a/src/SongFilter.hxx b/src/SongFilter.hxx
index 53200ed95..3d6963ed8 100644
--- a/src/SongFilter.hxx
+++ b/src/SongFilter.hxx
@@ -280,11 +280,4 @@ public:
 	SongFilter WithoutBasePrefix(const char *prefix) const noexcept;
 };
 
-/**
- * @return #TAG_NUM_OF_ITEM_TYPES on error
- */
-gcc_pure
-unsigned
-locate_parse_type(const char *str) noexcept;
-
 #endif