diff --git a/.travis.yml b/.travis.yml
index d4d3d338c1..f23dc37247 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,23 @@
 language: cpp
-sudo: required
-compiler: g++
 
-before_install:
-- sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-- sudo apt-get update -qq
+matrix:
+  fast_finish: true
+  include:
+    - os: linux
+      dist: trusty
+      compiler: gcc
+    - os: linux
+      dist: trusty
+      compiler: clang
+      env: CC=clang CXX=clang++
 
-install:
-- sudo apt-get install -qq g++-4.8 libeigen3-dev
-- export CXX="g++-4.8"
-
-before_script:
- - chmod +x build.sh
+addons:
+  apt:
+    packages:
+    - clang
+    - cmake
+    - g++
+    - gcc
+    - libeigen3-dev
 
 script: ./build.sh
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 12d688ee7d..351fe611ce 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,23 +40,23 @@ px4_add_module(
 		attitude_fw/ecl_controller.cpp
 		attitude_fw/ecl_pitch_controller.cpp
 		attitude_fw/ecl_roll_controller.cpp
-		attitude_fw/ecl_yaw_controller.cpp
 		attitude_fw/ecl_wheel_controller.cpp
+		attitude_fw/ecl_yaw_controller.cpp
+		EKF/airspeed_fusion.cpp
+		EKF/control.cpp
+		EKF/covariance.cpp
+		EKF/ekf.cpp
+		EKF/ekf_helper.cpp
+		EKF/estimator_interface.cpp
+		EKF/gps_checks.cpp
+		EKF/mag_fusion.cpp
+		EKF/optflow_fusion.cpp
+		EKF/sideslip_fusion.cpp
+		EKF/terrain_estimator.cpp
+		EKF/vel_pos_fusion.cpp
 		l1/ecl_l1_pos_controller.cpp
 		validation/data_validator.cpp
 		validation/data_validator_group.cpp
-		EKF/estimator_interface.cpp
-		EKF/ekf.cpp
-		EKF/ekf_helper.cpp
-		EKF/covariance.cpp
-		EKF/vel_pos_fusion.cpp
-		EKF/mag_fusion.cpp
-		EKF/gps_checks.cpp
-		EKF/airspeed_fusion.cpp
-		EKF/sideslip_fusion.cpp
-		EKF/optflow_fusion.cpp
-		EKF/control.cpp
-		EKF/terrain_estimator.cpp
 	DEPENDS
 		platforms__common
 	)
diff --git a/EKF/CMakeLists.txt b/EKF/CMakeLists.txt
index 0d7d6a93e9..10d92ad81a 100644
--- a/EKF/CMakeLists.txt
+++ b/EKF/CMakeLists.txt
@@ -33,47 +33,61 @@
 
 cmake_minimum_required(VERSION 2.8)
 
-project (ECL CXX)
-set(CMAKE_BUILD_TYPE Release)
-set(CMAKE_CXX_FLAGS "-DPOSIX_SHARED")
+project(ECL CXX)
 
+set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})
+
+# Find Eigen
 message("looking for FindEigen3.cmake in ${CMAKE_MODULE_PATH}")
 find_package(Eigen3 REQUIRED)
-
-if( NOT EIGEN3_INCLUDE_DIR )
-	message( FATAL_ERROR "Eigen3 not found.")
+if(NOT EIGEN3_INCLUDE_DIR)
+	message(FATAL_ERROR "Eigen3 not found.")
 endif()
 
-if( NOT EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/../matrix/.git" )
-message( SEND_ERROR "The git submodules are not available. Please run
-git submodule update --init --recursive"
-)
+set(MATRIX_DIR ${CMAKE_SOURCE_DIR}/../matrix)
+if(NOT EXISTS "${MATRIX_DIR}/.git")
+	message(SEND_ERROR "The git submodules are not available. Please run git submodule update --init --recursive")
 endif()
 
 include_directories(
-	./
-	../
-	../matrix
+	..
+	${MATRIX_DIR}
 	${EIGEN3_INCLUDE_DIR}
-)
+	)
+
 set(SRCS
-	estimator_interface.cpp
+	airspeed_fusion.cpp
+	control.cpp
+	covariance.cpp
 	ekf.cpp
 	ekf_helper.cpp
-	covariance.cpp
-	vel_pos_fusion.cpp
-	mag_fusion.cpp
-	gps_checks.cpp
-	airspeed_fusion.cpp
-	sideslip_fusion.cpp
-	control.cpp
+	estimator_interface.cpp
 	geo.cpp
+	gps_checks.cpp
+	mag_fusion.cpp
 	mathlib.cpp
-)
-add_definitions(-std=c++11 -Wall -Werror)
+	optflow_fusion.cpp
+	sideslip_fusion.cpp
+	terrain_estimator.cpp
+	vel_pos_fusion.cpp
+	)
 
-# Eigen throws various warnings
-add_definitions(-Wno-deprecated-declarations -Wno-enum-compare -Wno-unused-local-typedefs)
+add_definitions(-DPOSIX_SHARED)
+add_compile_options(
+	-pedantic
+	-std=c++11
+	-Wall
+	-Werror
+	-Wno-deprecated-declarations
+	-Wno-enum-compare
+	-Wno-unused-local-typedefs
+	-Wno-unused-parameter
+	)
+
+# clang tolerate unknown gcc options
+if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+	add_compile_options(-Wno-unknown-warning-option)
+endif()
 
 add_library(ecl SHARED ${SRCS})
diff --git a/EKF/ekf_helper.cpp b/EKF/ekf_helper.cpp
index 12ec0a9d2e..5f22cdf25a 100644
--- a/EKF/ekf_helper.cpp
+++ b/EKF/ekf_helper.cpp
@@ -42,6 +42,8 @@
 #include "ekf.h"
 #include "mathlib.h"
 
+using std::abs;
+
 // Reset the velocity states. If we have a recent and valid
 // gps measurement then use for velocity initialisation
 bool Ekf::resetVelocity()
diff --git a/EKF/mathlib.h b/EKF/mathlib.h
index 0c96a8f9d4..f84fedfb9c 100644
--- a/EKF/mathlib.h
+++ b/EKF/mathlib.h
@@ -52,7 +52,6 @@
 namespace math
 {
 // using namespace Eigen;
-using namespace std;
 
 float min(float val1, float val2);
 float max(float val1, float val2);
@@ -64,4 +63,4 @@ float degrees(float radians);
 #else
 #include <mathlib/mathlib.h>
 #endif //POSIX_SHARED
-#endif //MATHLIB_H
\ No newline at end of file
+#endif //MATHLIB_H
diff --git a/build.sh b/build.sh
index 5daff21095..281e3e3e12 100755
--- a/build.sh
+++ b/build.sh
@@ -36,7 +36,7 @@
 set -e
 
 # Build EKF shared library.
-mkdir Build
+mkdir Build -p
 cd Build
 cmake ../EKF
 make
diff --git a/matrix b/matrix
index db4374882b..cf924956d7 160000
--- a/matrix
+++ b/matrix
@@ -1 +1 @@
-Subproject commit db4374882bba122cb55370c5ea5efacbb8aa11c1
+Subproject commit cf924956d7d62ce18bfc4f8441e9177ddb69c0dc