diff --git a/cmake_modules/FindTRILINOS.cmake b/cmake_modules/FindTRILINOS.cmake
index 37456e5e8316..56441d57ad7f 100644
--- a/cmake_modules/FindTRILINOS.cmake
+++ b/cmake_modules/FindTRILINOS.cmake
@@ -39,7 +39,9 @@ ELSE (TRILINOS_LIBRARY_DIR OR TRILINOS_INCLUDE_DIR OR TRILINOS_ROOT)
         GET_FILENAME_COMPONENT(TRILINOS_ROOT "${Trilinos_INCLUDE_DIRS}" DIRECTORY)
         SET(TRILINOS_LIBRARY_DIR "${TRILINOS_ROOT}/lib")
     ELSE (Trilinos_FOUND) # Not found. This will raise an error
-        MESSAGE(FATAL_ERROR ${ERROR_NOT_FOUND_MESSAGE})
+        IF(NOT DEFINED MAKE_TRILINOS_OPTIONAL)
+            MESSAGE(FATAL_ERROR ${ERROR_NOT_FOUND_MESSAGE})
+        ENDIF(NOT DEFINED MAKE_TRILINOS_OPTIONAL)
     ENDIF (Trilinos_FOUND)
 ENDIF (TRILINOS_LIBRARY_DIR OR TRILINOS_INCLUDE_DIR OR TRILINOS_ROOT)