diff --git a/Makefile.in b/Makefile.in
index 283e19a..413d075 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,6 +1,6 @@
 
 CXX		:= @CXX@
-CXXFLAGS	:= -DHAVE_LIBSAMPLERATE -DHAVE_FFTW3 -DFFTW_DOUBLE_ONLY -DNO_THREAD_CHECKS -DNO_TIMING -DNDEBUG @CXXFLAGS@ @SRC_CFLAGS@ @SNDFILE_CFLAGS@ @FFTW_CFLAGS@ @Vamp_CFLAGS@ -Irubberband -I. -Isrc $(OPTFLAGS)
+CXXFLAGS	:= -DHAVE_LIBSAMPLERATE -DHAVE_FFTW3 -DFFTW_DOUBLE_ONLY -DNO_THREAD_CHECKS -DUSE_PTHREADS -DNO_TIMING -DNDEBUG @CXXFLAGS@ @SRC_CFLAGS@ @SNDFILE_CFLAGS@ @FFTW_CFLAGS@ @Vamp_CFLAGS@ -Irubberband -I. -Isrc $(OPTFLAGS)
 CFLAGS		:= @CFLAGS@ $(OPTFLAGS)
 LDFLAGS		:= @LDFLAGS@ -lpthread $(LDFLAGS)
 
diff --git a/README.txt b/README.txt
index 7901b7a..4139272 100644
--- a/README.txt
+++ b/README.txt
@@ -208,6 +208,9 @@ the supplied build files will handle these for you.)
    -DNO_THREADING
    Build without any multithread support.
 
+   -DUSE_PTHREADS
+   Use the pthreads library (required unless NO_THREADING or on Windows)
+
    -DPROCESS_SAMPLE_TYPE=float
    Select single precision for internal calculations. The default is
    double precision. Consider using for mobile architectures with