diff --git a/libs/audio/include/psemek/audio/literals.hpp b/libs/audio/include/psemek/audio/literals.hpp
index 22b2a4a5..92b004f2 100644
--- a/libs/audio/include/psemek/audio/literals.hpp
+++ b/libs/audio/include/psemek/audio/literals.hpp
@@ -8,22 +8,22 @@
 namespace psemek::audio::literals
 {
 
-	duration operator ""_s (unsigned long long value)
+	inline duration operator ""_s (unsigned long long value)
 	{
 		return duration::from_frames(value * frequency);
 	}
 
-	duration operator ""_ms (unsigned long long value)
+	inline duration operator ""_ms (unsigned long long value)
 	{
 		return duration::from_frames((value * frequency) / 1000);
 	}
 
-	duration operator ""_s (long double value)
+	inline duration operator ""_s (long double value)
 	{
 		return duration::from_frames(std::round(value * frequency));
 	}
 
-	duration operator ""_ms (long double value)
+	inline duration operator ""_ms (long double value)
 	{
 		return duration::from_frames(std::round(value * frequency / 1000.0));
 	}