diff --git a/app/src/main/rs/radix2.rsh b/app/src/main/rs/radix2.rsh
index 1002b66..ca1de1a 100644
--- a/app/src/main/rs/radix2.rsh
+++ b/app/src/main/rs/radix2.rsh
@@ -20,34 +20,35 @@ limitations under the License.
 #include "complex.rsh"
 #include "radix2_generated.rsh"
 
-static void radix2(complex_t *out, float *in, int N, int S, int L)
+static inline void dft2(complex_t *out0, complex_t *out1, complex_t in0, complex_t in1)
+{
+        *out0 = in0 + in1;
+        *out1 = in0 - in1;
+}
+
+static inline void fwd4(complex_t *out0, complex_t *out1, complex_t *out2, complex_t *out3,
+                float in0, float in1, float in2, float in3)
 {
-    // we only need 4 <= N forward FFTs
-    if (N == 4) {
-        float in0 = in[0];
-        float in1 = in[S];
-        float in2 = in[2 * S];
-        float in3 = in[3 * S];
         float a = in0 + in2;
         float b = in0 - in2;
         float c = in1 + in3;
-        out[0] = complex(a + c, 0.0f);
-        out[1] = complex(b, in3 - in1);
-        out[2] = complex(a - c, 0.0f);
-        out[3] = complex(b, in1 - in3);
+        *out0 = complex(a + c, 0.0f);
+        *out1 = complex(b, in3 - in1);
+        *out2 = complex(a - c, 0.0f);
+        *out3 = complex(b, in1 - in3);
+}
+
+static void radix2(complex_t *out, float *in, int N, int S)
+{
+    // we only need 4 <= N forward FFTs
+    if (N == 4) {
+        fwd4(out, out + 1, out + 2, out + 3, in[0], in[S], in[2 * S], in[3 * S]);
         return;
     }
-    radix2(out, in, N / 2, 2 * S, L + 1);
-    radix2(out + N / 2, in + S, N / 2, 2 * S, L + 1);
-    for (int k = 0; k < N / 2; ++k) {
-        int ke = k;
-        int ko = k + N / 2;
-        complex_t w = radix2_z[k << L];
-        complex_t even = out[ke];
-        complex_t odd = cmul(w, out[ko]);
-        out[ke] = even + odd;
-        out[ko] = even - odd;
-    }
+    radix2(out, in, N / 2, 2 * S);
+    radix2(out + N / 2, in + S, N / 2, 2 * S);
+    for (int k0 = 0, k1 = N / 2, l1 = 0; k0 < N / 2; ++k0, ++k1, l1 += S)
+        dft2(out + k0, out + k1, out[k0], cmul(radix2_z[l1], out[k1]));
 }
 
 #endif
\ No newline at end of file
diff --git a/app/src/main/rs/stft.rsh b/app/src/main/rs/stft.rsh
index a539199..2d1b01f 100644
--- a/app/src/main/rs/stft.rsh
+++ b/app/src/main/rs/stft.rsh
@@ -136,7 +136,7 @@ static void spectrum_analyzer(int amplitude)
         for (int i = 0; i < stft_N; ++i)
             input[i&(radix2_N-1)] += stft_w[i] * buffer[(i+n)&(stft_N-1)];
         // yep, were wasting 2x performance
-        radix2(output, input, radix2_N, 1, 0);
+        radix2(output, input, radix2_N, 1);
         for (int i = 0; i < radix2_N; ++i)
             input[i] = 0.0f;
         for (int j = spectrogram_height - 1; 0 < j; --j)