diff --git a/build/soong/Android.bp b/build/soong/Android.bp
index 8440cf90..6173f016 100644
--- a/build/soong/Android.bp
+++ b/build/soong/Android.bp
@@ -151,7 +151,7 @@ ignores_ftp_pptp_conntrack_failure_defaults {
     name: "ignores_ftp_pptp_conntrack_failure",
     soong_config_variables: {
         ignores_ftp_pptp_conntrack_failure: {
-            cppflags: ["DIGNORES_FTP_PPTP_CONNTRACK_FAILURE"],
+            cppflags: ["-DIGNORES_FTP_PPTP_CONNTRACK_FAILURE"],
         },
     },
 }