diff --git a/src/Makefile b/src/Makefile
index 1f68fc06..012de5be 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -441,6 +441,10 @@ ifdef ZDEBUG
 	CPPFLAGS+=-DZDEBUG
 endif
 
+ifdef DEVELOP
+	CPPFLAGS+=-DDEVELOP
+endif
+
 OPTS+=$(CPPFLAGS)
 
 # default EXENAME if all else fails