diff --git a/.travis.sh b/.travis.sh
index 209b08ee0..bb3b497ed 100755
--- a/.travis.sh
+++ b/.travis.sh
@@ -23,7 +23,7 @@ function build_and_test ()
   fi
 
   cmake $SOURCE_DIR \
-      -GTSAM_BUILD_UNSTABLE=$GTSAM_BUILD_UNSTABLE \
+      -DGTSAM_BUILD_UNSTABLE=$GTSAM_BUILD_UNSTABLE \
       -DGTSAM_BUILD_EXAMPLES_ALWAYS=$GTSAM_BUILD_EXAMPLES_ALWAYS \
       -DGTSAM_BUILD_TESTS=$GTSAM_BUILD_TESTS