diff --git a/src/makefile b/src/makefile
index 4ece5b14..3f23c219 100644
--- a/src/makefile
+++ b/src/makefile
@@ -71,6 +71,7 @@ ifneq ($(compiler_platform),)
   DYLIB_MINOR_NAME=$(LIBNAME).$(ZLOG_MAJOR).$(ZLOG_MINOR).$(DYLIBSUFFIX)
   DYLIB_MAJOR_NAME=$(LIBNAME).$(ZLOG_MAJOR).$(DYLIBSUFFIX)
   DYLIB_MAKE_CMD=$(CC) -dynamiclib -install_name $(INSTALL_LIBRARY_PATH)/$(DYLIB_MINOR_NAME) -o $(DYLIBNAME) $(LDFLAGS)
+  REAL_CFLAGS+= -D_DARWIN_C_SOURCE
 endif
 
 ifeq ($(uname_S),AIX)