diff --git a/stepmania/src/arch/Sound/RageSoundDriver_Generic_Software.cpp b/stepmania/src/arch/Sound/RageSoundDriver_Generic_Software.cpp
index 269b380dd1..d3d845185d 100644
--- a/stepmania/src/arch/Sound/RageSoundDriver_Generic_Software.cpp
+++ b/stepmania/src/arch/Sound/RageSoundDriver_Generic_Software.cpp
@@ -34,6 +34,8 @@ int RageSound_Generic_Software::DecodeThread_start( void *p )
 
 void RageSound_Generic_Software::Mix( int16_t *buf, int frames, int64_t frameno, int64_t current_frameno )
 {
+	RAGE_ASSERT_M( m_DecodeThread.IsCreated(), "RageSound_Generic_Software::StartMixing was never called" );
+
 	static SoundMixBuffer mix;
 
 	CHECKPOINT;