diff --git a/.travis.yml b/.travis.yml
index 88e37d1..89eadea 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,9 +6,10 @@ language: c
 addons:
   apt:
     sources:
-    - llvm-toolchain-trusty-4.0
+    - ubuntu-toolchain-r-test
+    - llvm-toolchain-precise-3.8
     packages:
-    - clang-4.0
+    - clang-3.8
 
 before_script:
   - gem install coveralls-lcov
diff --git a/scan_build.sh b/scan_build.sh
index 05d4fde..571ec4d 100755
--- a/scan_build.sh
+++ b/scan_build.sh
@@ -13,5 +13,7 @@ make clean > /dev/null
 
 scan_build=$(which scan-build)
 [ -z "$scan_build" ] && scan_build=$(find /usr/bin/ -name 'scan-build-*' | sort -nr | head -n1) || true
-[ -z "$scan_build" ] && { echo "couldn't find clang scan-build"; exit 1; } || true
-CFLAGS="" EXTRALIBS="" $scan_build make -f makefile.unix all CFLAGS="" EXTRALIBS=""
+[ -z "$scan_build" ] && { echo "couldn't find clang scan-build"; exit 1; } || echo "run $scan_build"
+export CFLAGS="-DUSE_LTM -DLTM_DESC -I/usr/include"
+export EXTRALIBS="-ltommath"
+$scan_build make -f makefile.unix all CFLAGS="$CFLAGS" EXTRALIBS="$EXTRALIBS"