diff --git a/src/MacAppBundle/CMakeLists.txt b/src/MacAppBundle/CMakeLists.txt
index 3a9cd9b1c1..5843f6a6c6 100644
--- a/src/MacAppBundle/CMakeLists.txt
+++ b/src/MacAppBundle/CMakeLists.txt
@@ -22,7 +22,7 @@ if(HOMEBREW_PREFIX)
     foreach(PTH_FILE ${HOMEBREW_PTH_FILES})
         file(READ ${PTH_FILE} ADDITIONAL_DIR)
 
-	string(STRIP ${ADDITIONAL_DIR} ADDITIONAL_DIR)
+	string(STRIP "${ADDITIONAL_DIR}" ADDITIONAL_DIR)
         string(REGEX REPLACE "^${HOMEBREW_PREFIX}/Cellar/([A-Za-z0-9_]+).*$" "\\1" LIB_NAME ${ADDITIONAL_DIR})
         string(REGEX REPLACE ".*libexec(.*)/site-packages" "libexec/${LIB_NAME}\\1" NEW_SITE_DIR ${ADDITIONAL_DIR})