diff --git a/src/song/StringFilter.cxx b/src/song/StringFilter.cxx
index 2f9c26039..9131595ae 100644
--- a/src/song/StringFilter.cxx
+++ b/src/song/StringFilter.cxx
@@ -22,7 +22,7 @@
 
 #include <assert.h>
 
-inline bool
+bool
 StringFilter::MatchWithoutNegation(const char *s) const noexcept
 {
 #if !CLANG_CHECK_VERSION(3,6)
diff --git a/src/song/StringFilter.hxx b/src/song/StringFilter.hxx
index a1a281f3c..588e34bdb 100644
--- a/src/song/StringFilter.hxx
+++ b/src/song/StringFilter.hxx
@@ -105,7 +105,9 @@ public:
 	gcc_pure
 	bool Match(const char *s) const noexcept;
 
-private:
+	/**
+	 * Like Match(), but ignore the "negated" flag.
+	 */
 	gcc_pure
 	bool MatchWithoutNegation(const char *s) const noexcept;
 };