diff --git a/GNUmakefile b/GNUmakefile
index fb33463..cebb242 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -11,9 +11,9 @@ WARNINGS = -Wall -Wextra -Wpedantic -Wformat=2 -Wstrict-aliasing=3 -Wstrict-over
 
 override CFLAGS ?= -g -O2 $(WARNINGS)
 override CFLAGS += -std=c99
-override CPPFLAGS ?= -D_FORTIFY_SOURCE=2 -D_DEFAULT_SOURCE
+override CPPFLAGS ?= -D_FORTIFY_SOURCE=2
 override CPPFLAGS += -DBM_VERSION=\"$(VERSION)\" -DBM_PLUGIN_VERSION=\"$(VERSION)-$(GIT_SHA1)\" -DINSTALL_LIBDIR=\"$(PREFIX)$(libdir)\"
-override CPPFLAGS += -Ilib
+override CPPFLAGS += -D_DEFAULT_SOURCE -Ilib
 
 libs = libbemenu.so
 bins = bemenu bemenu-run