diff --git a/cpp/src/arrow/CMakeLists.txt b/cpp/src/arrow/CMakeLists.txt
index fcdfaa21c71..0401ea8efd7 100644
--- a/cpp/src/arrow/CMakeLists.txt
+++ b/cpp/src/arrow/CMakeLists.txt
@@ -80,13 +80,13 @@ if(ARROW_WITH_ZSTD)
 endif()
 
 if(ARROW_ORC)
-  if(ORC_SOURCE STREQUAL "SYSTEM")
+  if(orc_SOURCE STREQUAL "SYSTEM")
     list(APPEND ARROW_STATIC_INSTALL_INTERFACE_LIBS orc::orc)
   endif()
 endif()
 
 if(ARROW_USE_GLOG)
-  if(GLOG_SOURCE STREQUAL "SYSTEM")
+  if(glog_SOURCE STREQUAL "SYSTEM")
     list(APPEND ARROW_STATIC_INSTALL_INTERFACE_LIBS glog::glog)
   endif()
 endif()