diff --git a/goal_src/jak1/engine/nav/navigate.gc b/goal_src/jak1/engine/nav/navigate.gc
index 2a26b2f917..39d2612c17 100644
--- a/goal_src/jak1/engine/nav/navigate.gc
+++ b/goal_src/jak1/engine/nav/navigate.gc
@@ -1310,7 +1310,8 @@
                       (let ((sv-96 (-> sv-80 sphere (-> sv-80 num-spheres)))
                             (f1-3 (vector-vector-xz-distance-squared sv-112 (-> sv-80 shape trans)))
                             (f0-9 (+ (-> sv-112 w) (-> sv-80 shape nav-radius))))
-                        (when (< f1-3 (square (+ 40960.0 f0-9)))
+                        ;; og:preserve-this added a NaN check here. it seems like some enemies have bogus positions (maybe on their first frame?)
+                        (when (and (< f1-3 (square (+ 40960.0 f0-9))) (not (is-nan? (-> sv-112 x))))
                           (vector-! (the-as vector sv-96) sv-112 (-> sv-80 mesh origin))
                           (set! (-> sv-96 w) f0-9)
                           (+! (-> sv-80 num-spheres) 1)))))