diff --git a/contrib/onelab/Makefile b/contrib/onelab/Makefile
index 766a1bf24fbd824718ca1bd420b7297ac41dc134..8d780dae8efb1c79b996e34695ad6fa6b1a1ab41 100644
--- a/contrib/onelab/Makefile
+++ b/contrib/onelab/Makefile
@@ -38,7 +38,7 @@ ifndef GMSH_DIR
 	@exit
 endif
 
-CPPFLAGS+=-I$(COMMON_DIR) -I$(ONELAB_DIR) -I$(MATHEX_DIR) -g
+CPPFLAGS+=-g -DONELAB_LOADER -I$(COMMON_DIR) -I$(ONELAB_DIR) -I$(MATHEX_DIR)
 VPATH=$(ONELAB_DIR):$(COMMON_DIR):$(MATHEX_DIR)
 
 OBJECTS=$(foreach OBJ, $(SOURCES), $(OBJDIR)/$(OBJ).o)