diff --git a/collada_urdf/CMakeLists.txt b/collada_urdf/CMakeLists.txt
index 54a1e05..ee25ed3 100644
--- a/collada_urdf/CMakeLists.txt
+++ b/collada_urdf/CMakeLists.txt
@@ -24,7 +24,7 @@ if ( NOT ASSIMP_FOUND )
   endif()
 endif()
 if( ASSIMP_FOUND )
-  if( ${ASSIMP_VERSION} STRGREATER "2.0.1150" )
+  if( NOT ${ASSIMP_VERSION} STRLESS "2.0.1150" )
     add_definitions(-DASSIMP_UNIFIED_HEADER_NAMES)
   endif()
   include_directories(${ASSIMP_INCLUDE_DIRS})