diff --git a/.travis.yml b/.travis.yml
index 48d9ac3a..bb6ca847 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,7 @@ matrix:
     # Ubuntu 14.04
     - env: Cmd='make gcc6install && CC=gcc-6 make clean uasan-test-zstd'
     - env: Cmd='make gcc6install libc6install && CC=gcc-6 make clean uasan-test-zstd32'
+    - env: Cmd='make gcc7install && CC=gcc-7 make clean uasan-test-zstd'
     - env: Cmd='make clang38install && CC=clang-3.8 make clean msan-test-zstd'
 
     - env: Cmd='make gcc6install && CC=gcc-6 make clean uasan-fuzztest'
diff --git a/Makefile b/Makefile
index c8f0ed4d..8157bdd9 100644
--- a/Makefile
+++ b/Makefile
@@ -231,31 +231,31 @@ msanregressiontest:
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63303
 
 usan: clean
-	$(MAKE) test CC=clang MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=undefined"
+	$(MAKE) test CC=clang MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=undefined -Werror"
 
 asan: clean
-	$(MAKE) test CC=clang MOREFLAGS="-g -fsanitize=address"
+	$(MAKE) test CC=clang MOREFLAGS="-g -fsanitize=address -Werror"
 
 asan-%: clean
-	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=address" $(MAKE) -C $(TESTDIR) $*
+	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=address -Werror" $(MAKE) -C $(TESTDIR) $*
 
 msan: clean
-	$(MAKE) test CC=clang MOREFLAGS="-g -fsanitize=memory -fno-omit-frame-pointer" HAVE_LZMA=0   # datagen.c fails this test for no obvious reason
+	$(MAKE) test CC=clang MOREFLAGS="-g -fsanitize=memory -fno-omit-frame-pointer -Werror" HAVE_LZMA=0   # datagen.c fails this test for no obvious reason
 
 msan-%: clean
-	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=memory -fno-omit-frame-pointer" FUZZER_FLAGS=--no-big-tests $(MAKE) -C $(TESTDIR) HAVE_LZMA=0 $*
+	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=memory -fno-omit-frame-pointer -Werror" FUZZER_FLAGS=--no-big-tests $(MAKE) -C $(TESTDIR) HAVE_LZMA=0 $*
 
 asan32: clean
 	$(MAKE) -C $(TESTDIR) test32 CC=clang MOREFLAGS="-g -fsanitize=address"
 
 uasan: clean
-	$(MAKE) test CC=clang MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=address,undefined"
+	$(MAKE) test CC=clang MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=address,undefined -Werror"
 
 uasan-%: clean
-	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=address,undefined" $(MAKE) -C $(TESTDIR) $*
+	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize-recover=signed-integer-overflow -fsanitize=address,undefined -Werror" $(MAKE) -C $(TESTDIR) $*
 
 tsan-%: clean
-	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=thread" $(MAKE) -C $(TESTDIR) $* FUZZER_FLAGS=--no-big-tests
+	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=thread -Werror" $(MAKE) -C $(TESTDIR) $* FUZZER_FLAGS=--no-big-tests
 
 apt-install:
 	sudo apt-get -yq --no-install-suggests --no-install-recommends --force-yes install $(APT_PACKAGES)
@@ -279,6 +279,9 @@ libc6install:
 gcc6install: apt-add-repo
 	APT_PACKAGES="libc6-dev-i386 gcc-multilib gcc-6 gcc-6-multilib" $(MAKE) apt-install
 
+gcc7install: apt-add-repo
+	APT_PACKAGES="libc6-dev-i386 gcc-multilib gcc-7 gcc-7-multilib" $(MAKE) apt-install
+
 gpp6install: apt-add-repo
 	APT_PACKAGES="libc6-dev-i386 g++-multilib gcc-6 g++-6 g++-6-multilib" $(MAKE) apt-install