diff --git a/.travis.yml b/.travis.yml
index 9e74a97b..60927e90 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -110,7 +110,7 @@ install:
 
 before_script:
     - |
-      if [ "BUILD_SYSTEM" == "cmake" ]; then
+      if [ "$BUILD_SYSTEM" == "cmake" ]; then
         # Make build directory and generate CMake build files
         mkdir -p ${CMAKE_BUILD_DIR} && cd ${CMAKE_BUILD_DIR}
         cmake .. -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DFIX_BUGS=ON -DWARNINGS=ON -DWARNINGS_ALL=ON
@@ -119,7 +119,7 @@ before_script:
 
 script:
     - |
-      if [ "BUILD_SYSTEM" == "cmake" ]; then
+      if [ "$BUILD_SYSTEM" == "cmake" ]; then
         # CMake build
         cd ${CMAKE_BUILD_DIR}
         cmake --build . --config $BUILD_TYPE --parallel $JOBS