diff --git a/src/frontend/com_fft.c b/src/frontend/com_fft.c
index d3b68056a..8b74414fc 100644
--- a/src/frontend/com_fft.c
+++ b/src/frontend/com_fft.c
@@ -63,6 +63,7 @@ com_fft(wordlist *wl)
 
 #ifdef HAVE_LIBFFTW3
     fpts = length/2 + 1;
+    scale = ((double)length)/2.0;
 #else
     /* size of fft input vector is power of two and larger or equal than spice vector */
     N = 1;
@@ -72,6 +73,7 @@ com_fft(wordlist *wl)
         M++;
     }
     fpts = N/2 + 1;
+    scale = ((double)N)/2;
 #endif
 
     win = TMALLOC(double, length);
@@ -178,7 +180,6 @@ com_fft(wordlist *wl)
 
         fftw_execute(plan_forward);
 
-        scale = (double) fpts - 1.0;
         fdvec[i][0].cx_real = out[0][0]/scale/2.0;
         fdvec[i][0].cx_imag = 0.0;
         for (j = 1; j < fpts; j++) {
@@ -215,7 +216,6 @@ com_fft(wordlist *wl)
         rffts(in, M, 1);
         fftFree();
 
-        scale = (double) fpts - 1.0;
         /* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
         fdvec[i][0].cx_real = in[0]/scale/2.0;
         fdvec[i][0].cx_imag = 0.0;
diff --git a/src/maths/cmaths/cmath4.c b/src/maths/cmaths/cmath4.c
index af661e968..04b0b5142 100644
--- a/src/maths/cmaths/cmath4.c
+++ b/src/maths/cmaths/cmath4.c
@@ -774,7 +774,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
 
         fftw_execute(plan_forward);
 
-        scale = (double) fpts - 1.0;
+        scale = ((double)length)/2.0;
         outdata[0].cx_real = out[0][0]/scale/2.0;
         outdata[0].cx_imag = 0.0;
         for (i = 1; i < fpts; i++) {
@@ -803,7 +803,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
         rffts(datax, M, 1);
         fftFree();
 
-        scale = (double) fpts - 1.0;
+        scale = ((double)N)/2;
         /* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
         outdata[0].cx_real = datax[0]/scale/2.0;
         outdata[0].cx_imag = 0.0;