diff --git a/sndlock.cpp b/sndlock.cpp
index d7983b4..4470ea3 100644
--- a/sndlock.cpp
+++ b/sndlock.cpp
@@ -87,7 +87,7 @@ static void dsp_thread()
             if(buf_out_offset == sizeof(buf_out)) {
                 for(int i=0;i<SND_PCHAN;i++)
                     for(int j=0;j<SND_BUFLEN;j++) {
-                        buf_out[2*j+i] = scale*sin(phase_out[i]*2.0*M_PI/(double)UINT32_MAX);
+                        buf_out[SND_PCHAN*j+i] = scale*sin(phase_out[i]*2.0*M_PI/(double)UINT32_MAX);
                         phase_out[i] += ftw[i];  // wraps on overflow
                     }
                 buf_out_offset = 0;