diff --git a/cmds/installd/commands.c b/cmds/installd/commands.c
index 669f403e6..a86abe1b7 100644
--- a/cmds/installd/commands.c
+++ b/cmds/installd/commands.c
@@ -685,9 +685,13 @@ int dexopt(const char *apk_path, uid_t uid, int is_public,
     /* Before anything else: is there a .odex file?  If so, we have
      * precompiled the apk and there is nothing to do here.
      */
-    sprintf(out_path, "%s%s", apk_path, ".odex");
-    if (stat(out_path, &dex_stat) == 0) {
-        return 0;
+    strcpy(out_path, apk_path);
+    end = strrchr(out_path, '.');
+    if (end != NULL) {
+        strcpy(end, ".odex");
+        if (stat(out_path, &dex_stat) == 0) {
+            return 0;
+        }
     }
 
     if (create_cache_path(out_path, apk_path)) {