diff --git a/bootstrap.c b/bootstrap.c
index 3f69c55..29c0e40 100644
--- a/bootstrap.c
+++ b/bootstrap.c
@@ -181,6 +181,12 @@ static char *extract_neopig(const char *self_path, long tar_offset) {
         int is_neopig_py = (neopig_pos && py_ext && py_ext > neopig_pos);
         int is_requirements = (req_file != NULL);
 
+        /* Debug: show neopig-related files */
+        if (neopig_pos || req_file) {
+            fprintf(stderr, "  [DEBUG] Found: %s (neopig=%d, py=%d, req=%d)\n",
+                   filename, neopig_pos != NULL, py_ext != NULL, req_file != NULL);
+        }
+
         if (is_neopig_py || is_requirements) {
             /* Extract this file */
             char out_path[4096];
@@ -207,9 +213,9 @@ static char *extract_neopig(const char *self_path, long tar_offset) {
                 found_any = 1;
                 if (is_neopig_py) {
                     char *basename = neopig_pos + 8;
-                    printf("  Extracted: %s\n", basename);
+                    fprintf(stderr, "  Extracted: %s\n", basename);
                 } else {
-                    printf("  Extracted: requirements.txt\n");
+                    fprintf(stderr, "  Extracted: requirements.txt\n");
                 }
 
                 /* Skip padding to 512 boundary */