diff --git a/src/gig_callback.c b/src/gig_callback.c
index 4e08fe9c..42e11046 100644
--- a/src/gig_callback.c
+++ b/src/gig_callback.c
@@ -180,6 +180,10 @@ callback_binding(ffi_cif *cif, gpointer ret, gpointer *ffi_args, gpointer user_d
     SCM s_args = SCM_EOL;
     SCM s_ret;
 
+    // When using GLib thread functions, this could be the entrypoint
+    // into Guile for this thread.
+    scm_init_guile();
+
     g_assert(cif != NULL);
     g_assert(ret != NULL);
     g_assert(ffi_args != NULL);
diff --git a/src/gig_function.c b/src/gig_function.c
index e3960e30..0cc4bdd0 100644
--- a/src/gig_function.c
+++ b/src/gig_function.c
@@ -1,4 +1,4 @@
-// Copyright (C) 2018, 2019, 2020 Michael L. Gran
+// Copyright (C) 2018, 2019, 2020, 2021 Michael L. Gran
 
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -626,6 +626,10 @@ function_binding(ffi_cif *cif, gpointer ret, gpointer *ffi_args, gpointer user_d
     GObject *self = NULL;
     SCM s_args = SCM_UNDEFINED;
 
+    // When using GLib thread functions, could this be the entrypoint
+    // into Guile for this thread?
+    scm_init_guile();
+
     g_assert(cif != NULL);
     g_assert(ret != NULL);
     g_assert(ffi_args != NULL);