diff --git a/lal/src/fft/IntelRealFFT_source.c b/lal/src/fft/IntelRealFFT_source.c
index 9207845c48800f386e424c500de9e80209f3c860..2ecff1954fc09bd2407a508f85b4402ebbe11392 100644
--- a/lal/src/fft/IntelRealFFT_source.c
+++ b/lal/src/fft/IntelRealFFT_source.c
@@ -295,6 +295,7 @@ int POWER_SPECTRUM_FUNCTION(REAL_VECTOR_TYPE * spec, const REAL_VECTOR_TYPE * da
         REAL_TYPE re = plan->tmp[2 * k - 1];
         REAL_TYPE im = plan->tmp[2 * k];
         spec->data[k] = re * re + im * im;
+        spec->data[k] *= 2.0;  /* accounts for negative frequency part */
     }
 
     /* Nyquist frequency */