diff --git a/rebar.config b/rebar.config
index 21d678e..815f982 100644
--- a/rebar.config
+++ b/rebar.config
@@ -1,3 +1,3 @@
 {erl_opts, [
-  {platform_define, "(R14|R15)", "no_sha_hmac"}
+  {platform_define, "(R14|R15)", 'no_sha_hmac'}
 ]}.