diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -459,10 +459,10 @@
   if (LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL STREQUAL "LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL-NOTFOUND")
     set(LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL "")
   endif()
+endif()
 
-  if (NOT LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL STREQUAL "")
-    include_directories("${LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL}")
-  endif()
+if (NOT "${LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL}" STREQUAL "")
+  include_directories("${LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL}")
 endif()
 
 # Add source code. This also contains all of the logic for deciding linker flags