diff --git a/Tools/ardupilotwaf/boards.py b/Tools/ardupilotwaf/boards.py
index 6f53922836732a..8b8a478ece354b 100644
--- a/Tools/ardupilotwaf/boards.py
+++ b/Tools/ardupilotwaf/boards.py
@@ -462,8 +462,8 @@ def configure_env(self, cfg, env):
         # We always want to use PRI format macros
         cfg.define('__STDC_FORMAT_MACROS', 1)
 
-        if cfg.options.disable_ekf2:
-            env.CXXFLAGS += ['-DHAL_NAVEKF2_AVAILABLE=0']
+        if cfg.options.enable_ekf2:
+            env.CXXFLAGS += ['-DHAL_NAVEKF2_AVAILABLE=1']
 
         if cfg.options.disable_ekf3:
             env.CXXFLAGS += ['-DHAL_NAVEKF3_AVAILABLE=0']
diff --git a/Tools/autotest/sim_vehicle.py b/Tools/autotest/sim_vehicle.py
index 0c849f6405b6b8..517f507b84a4ec 100755
--- a/Tools/autotest/sim_vehicle.py
+++ b/Tools/autotest/sim_vehicle.py
@@ -378,8 +378,8 @@ def do_build(opts, frame_options):
     if opts.math_check_indexes:
         cmd_configure.append("--enable-math-check-indexes")
 
-    if opts.disable_ekf2:
-        cmd_configure.append("--disable-ekf2")
+    if opts.enable_ekf2:
+        cmd_configure.append("--enable-ekf2")
 
     if opts.disable_ekf3:
         cmd_configure.append("--disable-ekf3")
@@ -1299,7 +1299,7 @@ def generate_frame_help():
 group_sim.add_option("--fram-storage",
                      action='store_true',
                      help="use fram storage emulation")
-group_sim.add_option("--disable-ekf2",
+group_sim.add_option("--enable-ekf2",
                      action='store_true',
                      help="disable EKF2 in build")
 group_sim.add_option("--disable-ekf3",
diff --git a/wscript b/wscript
index 7f0a2e14dfe356..659f23a76d5932 100644
--- a/wscript
+++ b/wscript
@@ -360,10 +360,10 @@ configuration in order to save typing.
         default=False,
         help='Use flash storage emulation.')
 
-    g.add_option('--disable-ekf2',
+    g.add_option('--enable-ekf2',
         action='store_true',
         default=False,
-        help='Configure without EKF2.')
+        help='Configure with EKF2.')
 
     g.add_option('--disable-ekf3',
         action='store_true',