diff --git a/scripts/cmake/ExternalProjectBoost.cmake b/scripts/cmake/ExternalProjectBoost.cmake
index a381734682f3ce49b1b11aea94637d825dd045cc..530ca40741b4b4afda948e75b19c4591eb7e8b92 100644
--- a/scripts/cmake/ExternalProjectBoost.cmake
+++ b/scripts/cmake/ExternalProjectBoost.cmake
@@ -30,7 +30,7 @@ SET(BOOST_LIBS_TO_BUILD
 IF(NOT Boost_INCLUDE_DIRS)
 	SET(Boost_USE_STATIC_LIBS ON)
 	IF(OGS_LIBS_DIR)
-		SET(BOOST_ROOT ${OGS_LIBS_DIR/boost})
+		SET(BOOST_ROOT ${OGS_LIBS_DIR}/boost)
 	ENDIF()
 	FIND_PACKAGE(Boost 1.48.0 COMPONENTS ${BOOST_LIBS_TO_BUILD})
 	IF(Boost_FOUND)