diff --git a/src/clj_pebble/core.clj b/src/clj_pebble/core.clj
index e098449..dde7323 100644
--- a/src/clj_pebble/core.clj
+++ b/src/clj_pebble/core.clj
@@ -37,7 +37,7 @@
          pebble-fn# (make-function f#)]
      (.put (.getFunctions @engine) ~fn-name pebble-fn#)))
 
-(defn prepare-context-map [context]
+(defn- prepare-context-map [context]
   (if context
     (stringify-keys context)
     {}))