diff --git a/sndlock.cpp b/sndlock.cpp
index 42acbd4..fe7ce5b 100644
--- a/sndlock.cpp
+++ b/sndlock.cpp
@@ -72,7 +72,7 @@ static void dsp_thread()
             if(buf_out_idx == SND_BUFLEN*SND_PCHAN) {
                 uint32_t ftw = frequency*(float)UINT32_MAX/SND_RATE;
                 for(int i=0;i<SND_BUFLEN;i++) {
-                    buf_out[2*i] = buf_out[2*i+1] = (INT16_MAX-1)*sin(phase*2.0f*(float)M_PI/(float)UINT32_MAX);
+                    buf_out[2*i] = buf_out[2*i+1] = (INT16_MAX-1)*sinf(phase*2.0f*(float)M_PI/(float)UINT32_MAX);
                     phase += ftw;
                 }
                 buf_out_idx = 0;