diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3db39241d..e41f37c6d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,7 @@ set(OPS_EXTERNALS_DIR ${PROJECT_SOURCE_DIR}/OTHER/)
 set(OPS_BUNDLED_DIR ${PROJECT_SOURCE_DIR}/OTHER/)
 set(OPS_SRC_DIR ${PROJECT_SOURCE_DIR}/SRC/)
 include(OpenSeesFunctions)
+
 include(${PROJECT_SOURCE_DIR}/Conf.cmake)
 
 set_property(CACHE OPS_FINAL_TARGET PROPERTY STRINGS 
@@ -416,6 +417,17 @@ if(FMK)
     )    
 endif()
 
+#----------------------------
+# Extensions
+#----------------------------
+message("OPS >>> Configuring OpenSees extensions")
+foreach(extension IN LISTS OPS_Element_List OPS_Extension_List)
+    string(TOUPPER "${extension}" ext_flag) 
+    set(ext_flag "_${ext_flag}")
+    message("    Adding definition '${ext_flag}'")
+    add_compile_definitions(${ext_flag})
+endforeach()
+
 #----------------------------
 # Renderer
 #----------------------------