diff --git a/include/fft/fft.h b/include/fft/fft.h
index e1a8a18..4ac8ac5 100644
--- a/include/fft/fft.h
+++ b/include/fft/fft.h
@@ -8,4 +8,4 @@
 #define FFT_BIN(num, re) (uint16_t)((float)(num + 0.5) * re)
 #define FFT_INDEX(freq, re) (uint16_t)((float)freq / re)
 
-int FFT(q15_t *data);
+void FFT(q15_t *data);
diff --git a/src/fft/fft.c b/src/fft/fft.c
index 71d4f76..79f9fac 100644
--- a/src/fft/fft.c
+++ b/src/fft/fft.c
@@ -84,7 +84,7 @@ static inline void butterfly(q15_t *data) {
     }
 }
 
-int FFT(q15_t *data) {
+void FFT(q15_t *data) {
     for (uint16_t i = 0; i < N; i++) {
         res[Re(i)] = data[i];  // real
         res[Im(i)] = 0;        // imaginary
@@ -93,6 +93,4 @@ int FFT(q15_t *data) {
     butterfly(res);
     bitreversal((q31_t *)res);
     for (uint16_t i = 0; i < N; i++) data[i] = (q15_t)abs(res[Re(i)]);
-
-    return 0;
 }