--- lib-src/libnyquist/nyqsrc/fft.c
+++ lib-src/libnyquist/nyqsrc/fft.c
@@ -177,7 +177,7 @@
         temp_fft[i + len] = 0.0F;
     }
     /* perform the fft: */
-    fftnf(1, (const int *) &len, temp_fft, temp_fft + len, 1, -1.0);
+    fftnf(1, &len, temp_fft, temp_fft + len, 1, -1.0);
     setelement(result, 0, cvflonum(temp_fft[0]));
     for (i = 2; i < len; i += 2) {
         setelement(result, i - 1, cvflonum(temp_fft[i / 2] * 2));