diff --git a/tests/Makefile b/tests/Makefile
index 06af136..e48c9aa 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -4,7 +4,7 @@ HOSTCC = cc
 PKG_CONFIG ?= pkg-config
 CFLAGS ?= -O2 -g
 UNIT_CPPFLAGS = -I..
-UNIT_CFLAGS = -std=c99 -Wall -Wextra
+UNIT_CFLAGS = -Wall -Wextra
 HOST_CFLAGS = -std=c99 -Wall -Wextra
 TEXT_CFLAGS = $(shell $(PKG_CONFIG) --cflags pangocairo cairo fontconfig)
 TEXT_LIBS = $(shell $(PKG_CONFIG) --libs pangocairo cairo fontconfig)