diff --git a/etc/SuperBuild/CMakeLists.txt b/etc/SuperBuild/CMakeLists.txt
index 7364f87a..e99b39db 100644
--- a/etc/SuperBuild/CMakeLists.txt
+++ b/etc/SuperBuild/CMakeLists.txt
@@ -58,8 +58,8 @@ set(CMAKE_FIND_FRAMEWORK LAST)
 # https://stackoverflow.com/questions/45414507/pass-a-list-of-prefix-paths-to-externalproject-add-in-cmake-args
 string(REPLACE ";" "|" CMAKE_MODULE_PATH_TMP "${CMAKE_MODULE_PATH}")
 string(REPLACE ";" "|" CMAKE_PREFIX_PATH_TMP "${CMAKE_PREFIX_PATH}")
-string(REPLACE " " "|" CMAKE_CXX_FLAGS_TMP "${CMAKE_CXX_FLAGS}")
-string(REPLACE " " "|" CMAKE_C_FLAGS_TMP "${CMAKE_C_FLAGS}")
+string(REPLACE ";" "|" CMAKE_CXX_FLAGS_TMP "${CMAKE_CXX_FLAGS}")
+string(REPLACE ";" "|" CMAKE_C_FLAGS_TMP "${CMAKE_C_FLAGS}")
 
 # Common arguments for building external projects.
 set(TLRENDER_EXTERNAL_ARGS