diff --git a/.travis.yml b/.travis.yml
index 84b8b7f..5da1f51 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -30,10 +30,10 @@ before_install:
       brew install libusb;
     fi
 
-# build by simply using the Makefile
+# build using the Makefile, treat all warnings as errors
 script:
-  - make
-  - make misc
+  - make EXTRA_CFLAGS=-Werror
+  - make misc EXTRA_CFLAGS=-Werror
 
 # turn off email notifications
 notifications:
diff --git a/Makefile b/Makefile
index 881cf83..ee07786 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 CC ?= gcc
-CFLAGS = -g -O0 -Wall -Wextra
+CFLAGS = -g -O0 -Wall -Wextra $(EXTRA_CFLAGS)
 CFLAGS += -std=c99 $(DEFINES)
 CFLAGS += -Iinclude/