diff --git a/lib/zip_source_file_win32.c b/lib/zip_source_file_win32.c
index 6547fc2..0dea2c1 100644
--- a/lib/zip_source_file_win32.c
+++ b/lib/zip_source_file_win32.c
@@ -115,7 +115,7 @@
         break;
     default:
         zip_error_set(&ctx->error, ZIP_ER_SEEK, EINVAL);
-        return -1;
+        return false;
     }
 
     li.QuadPart = (LONGLONG)offset;