diff --git a/SConstruct b/SConstruct
index 17df024c5594..5ea7aece3780 100755
--- a/SConstruct
+++ b/SConstruct
@@ -506,7 +506,7 @@ for env in [test_env, client_env, env]:
 
         if env['harden'] and env["PLATFORM"] != 'win32':
             env.AppendUnique(CCFLAGS = ["-fPIE"])
-            if not env["have_fortify"] and "-O0" not in env["opt"]:
+            if not env.get("have_fortify") and "-O0" not in env["opt"]:
                 env.AppendUnique(CPPDEFINES = ["_FORTIFY_SOURCE=2"])
             
             if env["PLATFORM"] == 'darwin':