diff --git a/src/matrix/Makefile b/src/matrix/Makefile
index 398179a35..c903fbfd4 100644
--- a/src/matrix/Makefile
+++ b/src/matrix/Makefile
@@ -10,7 +10,6 @@ include ../kaldi.mk
 
 # you can uncomment matrix-lib-speed-test if you want to do the speed tests.
 
-TESTFILES = matrix-lib-test sparse-matrix-test numpy-array-test #matrix-lib-speed-test
 
 OBJFILES = kaldi-matrix.o kaldi-vector.o packed-matrix.o sp-matrix.o tp-matrix.o \
            matrix-functions.o qr.o srfft.o compressed-matrix.o \


diff --git a/src/util/kaldi-thread.cc b/src/util/kaldi-thread.cc
index 4573e24f1..4af4e73ea 100644
--- a/src/util/kaldi-thread.cc
+++ b/src/util/kaldi-thread.cc
@@ -22,7 +22,7 @@
 #include "util/kaldi-thread.h"
 
 namespace kaldi {
-int32 g_num_threads = 4;  // Initialize this global variable.
+int32 g_num_threads = 1;  // Initialize this global variable.
 
 MultiThreadable::~MultiThreadable() {
   // default implementation does nothing

diff --git a/src/ivector/ivector-extractor.cc b/src/ivector/ivector-extractor.cc
index c3a122281..71d37256d 100644
--- a/src/ivector/ivector-extractor.cc
+++ b/src/ivector/ivector-extractor.cc
@@ -195,7 +195,7 @@ void IvectorExtractor::ComputeDerivedVars() {
   // could because some tasks finish before others.
   {
     TaskSequencerConfig sequencer_opts;
-    sequencer_opts.num_threads = g_num_threads;
+    sequencer_opts.num_threads = 0;
     TaskSequencer<IvectorExtractorComputeDerivedVarsClass> sequencer(
         sequencer_opts);
     for (int32 i = 0; i < NumGauss(); i++)

