diff --git a/.travis.yml b/.travis.yml
index 53cdb20..e5dc18d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,31 +6,16 @@ matrix:
     - os: linux
       dist: trusty
       sudo: false
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-          packages:
-            - gcc-7
-      env:
-        - PKGI_CC=gcc-7
+      compiler: gcc
 
     - os: linux
       dist: trusty
       sudo: false
-      addons:
-        apt:
-          sources:
-            - llvm-toolchain-trusty-5.0
-          packages:
-            - clang-5.0
-      env:
-        - PKGI_CC=clang-5.0
+      compiler: clang
 
     - os: osx
       osx_image: xcode9.1
-      env:
-        - PKGI_CC=clang
+      compiler: clang
 
 script:
-  - CC=${PKGI_CC} make
+  - make
diff --git a/makefile b/makefile
index 54112f7..9797369 100644
--- a/makefile
+++ b/makefile
@@ -10,7 +10,7 @@ SRC=${wildcard pkg2zip*.c} puff.c
 OBJ=${SRC:.c=.o}
 DEP=${SRC:.c=.d}
 
-CFLAGS=-pipe -fvisibility=hidden -Wall -Wextra -Werror -DNDEBUG -O2
+CFLAGS=-std=c99 -pipe -fvisibility=hidden -Wall -Wextra -Werror -DNDEBUG -D_GNU_SOURCE -O2
 LDFLAGS=-s
 
 .PHONY: all clean
diff --git a/pkg2zip_sys.c b/pkg2zip_sys.c
index 52a7291..338945a 100644
--- a/pkg2zip_sys.c
+++ b/pkg2zip_sys.c
@@ -222,4 +222,4 @@ void sys_vstrncat(char* dst, size_t n, const char* format, ...)
     va_end(args);
 
     strncat(dst, temp, n - strlen(dst) - 1);
-}
\ No newline at end of file
+}