diff --git a/src/tox_current_env/hooks.py b/src/tox_current_env/hooks.py
index c59aef7..87d5f3e 100644
--- a/src/tox_current_env/hooks.py
+++ b/src/tox_current_env/hooks.py
@@ -208,6 +208,7 @@ def tox_runtest(venv, redirect):
             sep="\n",
             file=config.option.print_deps_to,
         )
+        config.option.print_deps_to.flush()
         ret = True
 
     if config.option.print_extras_to:
@@ -216,6 +217,7 @@ def tox_runtest(venv, redirect):
             sep="\n",
             file=config.option.print_extras_to,
         )
+        config.option.print_extras_to.flush()
         ret = True
 
     return ret