4 files changed, 4 insertions, 3 deletions

diff --git a/other/travis/env-linux.sh b/other/travis/env-linux.sh
index a8b1d5ae..10b4fe82 100644
--- a/other/travis/env-linux.sh
+++ b/other/travis/env-linux.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 CMAKE=cmake
-CMAKE_EXTRA_FLAGS="-DFORMAT_TEST=ON"
+CMAKE_EXTRA_FLAGS="$CMAKE_EXTRA_FLAGS -DFORMAT_TEST=ON"
 NPROC=`nproc`
 CURDIR=$PWD
 
diff --git a/other/travis/env-osx.sh b/other/travis/env-osx.sh
index 86d16ade..b68a8651 100644
--- a/other/travis/env-osx.sh
+++ b/other/travis/env-osx.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 CMAKE=cmake
-CMAKE_EXTRA_FLAGS=""
+CMAKE_EXTRA_FLAGS="$CMAKE_EXTRA_FLAGS"
 NPROC=`sysctl -n hw.ncpu`
 CURDIR=$PWD
 
diff --git a/other/travis/env-windows.sh b/other/travis/env-windows.sh
index 44f486af..0ea1f726 100644
--- a/other/travis/env-windows.sh
+++ b/other/travis/env-windows.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 CMAKE=$ARCH-w64-mingw32.shared-cmake
-CMAKE_EXTRA_FLAGS="-DBOOTSTRAP_DAEMON=OFF -DCOMPILE_AS_CXX=ON"
+CMAKE_EXTRA_FLAGS="$CMAKE_EXTRA_FLAGS -DBOOTSTRAP_DAEMON=OFF -DCOMPILE_AS_CXX=ON"
 NPROC=`nproc`
 CURDIR=/work
 
diff --git a/other/travis/env.sh b/other/travis/env.sh
index f899eb88..bb19d46d 100644
--- a/other/travis/env.sh
+++ b/other/travis/env.sh
@@ -7,6 +7,7 @@ export LD_LIBRARY_PATH=$CACHE_DIR/lib
 export PKG_CONFIG_PATH=$CACHE_DIR/lib/pkgconfig
 export ASTYLE=$CACHE_DIR/astyle/build/gcc/bin/astyle
 export CFLAGS="-O3 -DTRAVIS_ENV=1"
+export CMAKE_EXTRA_FLAGS="-DERROR_ON_WARNING=ON"
 
 BUILD_DIR=_build