diff -up gnuradio-3.5.1/gnuradio-core/src/lib/filter/qa_gri_mmse_fir_interpolator_cc.cc.orig gnuradio-3.5.1/gnuradio-core/src/lib/filter/qa_gri_mmse_fir_interpolator_cc.cc
--- gnuradio-3.5.1/gnuradio-core/src/lib/filter/qa_gri_mmse_fir_interpolator_cc.cc.orig	2011-05-05 14:19:10.000000000 +0200
+++ gnuradio-3.5.1/gnuradio-core/src/lib/filter/qa_gri_mmse_fir_interpolator_cc.cc	2012-01-13 15:12:31.959981553 +0100
@@ -31,6 +31,7 @@
 #include <stdio.h>
 #include <cmath>
 #include <stdexcept>
+#include <unistd.h>
 
 #define	NELEM(x) (sizeof (x) / sizeof (x[0]))