diff --git a/install.sh b/install.sh
index 32e5dc4d4e..7c8a865ef5 100755
--- a/install.sh
+++ b/install.sh
@@ -78,7 +78,7 @@ build_dir=./build
 rm -rf ${build_dir}
 
 if ($mpi_enabled); then
-    if [[ ${mpi_dir} -eq "" ]]; then
+    if [[ ${mpi_dir} == "" ]]; then
         echo "MPI flag enabled but path to MPI installation not specified.  See --mpi_home command line argument."
         exit 1
     else