diff --git a/.travis.yml b/.travis.yml
index 2b06c1c8f..61690333c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,11 +8,13 @@ env:
     - CC=gcc-4.7
     - CXX=g++-4.7
     - ARTIQ_NO_HARDWARE=1
+    - BUILD_SOC=0
     - secure: "DUk/Ihg8KbbzEgPF0qrHqlxU8e8eET9i/BtzNvFddIGX4HP/P2qz0nk3cVkmjuWhqJXSbC22RdKME9qqPzw6fJwJ6dpJ3OR6dDmSd7rewavq+niwxu52PVa+yK8mL4yf1terM7QQ5tIRf+yUL9qGKrZ2xyvEuRit6d4cFep43Ws="
 before_install:
-  - echo "$TRAVIS_COMMIT_MSG" | grep -vq "\[soc\]"; export SOC=$?; true
+  - if echo "$TRAVIS_COMMIT_MSG" | grep -q "\[soc\]"; then BUILD_SOC=1; fi
+  - if [ $TRAVIS_PULL_REQUEST != false ]; then BUILD_SOC=0; fi
   - ./.travis/get-toolchain.sh
-  - ./.travis/get-xilinx.sh
+  - if [ $BUILD_SOC -ne 0 ]; then ./.travis/get-xilinx.sh; fi
   - ./.travis/get-anaconda.sh pip coverage numpy scipy sphinx h5py pyserial dateutil
   - source $HOME/miniconda/bin/activate py34
   - ./.travis/get-misoc.sh
@@ -25,7 +27,7 @@ script:
   - make -C doc/manual html
   - cd misoc; python make.py -X ../soc -t artiq build-headers build-bios; cd ..
   - make -C soc/runtime
-  - if [ $SOC -ne 0 ]; then cd misoc python make.py -X ../soc -t artiq build-bitstream; cd ..; fi
+  - if [ $BUILD_SOC -ne 0 ]; then cd misoc; python make.py -X ../soc -t artiq build-bitstream; cd ..; fi
 after_success:
   coveralls
 notifications: