diff --git a/include/isocline.h b/include/isocline.h
--- a/include/isocline.h
+++ b/include/isocline.h
@@ -415,13 +415,13 @@
 const char* ic_completion_input( ic_completion_env_t* cenv, long* cursor );
 
 /// Get the completion argument passed to `ic_set_completer`.
-void* ic_completion_arg( ic_completion_env_t* cenv );
+void* ic_completion_arg( const ic_completion_env_t* cenv );
 
 /// Do we have already some completions?
-bool ic_has_completions( ic_completion_env_t* cenv );
+bool ic_has_completions( const ic_completion_env_t* cenv );
 
 /// Do we already have enough completions and should we return if possible? (for improved latency)
-bool ic_stop_completing(ic_completion_env_t* cenv);
+bool ic_stop_completing( const ic_completion_env_t* cenv);
 
 
 /// Primitive completion, cannot be used with most transformers (like `ic_complete_word` and `ic_complete_qword`).
diff --git a/isocline.cabal b/isocline.cabal
--- a/isocline.cabal
+++ b/isocline.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           isocline
-version:        1.0.8
+version:        1.0.9
 synopsis:       A portable alternative to GNU Readline
 description:    ![logo](https://raw.githubusercontent.com/daanx/isocline/main/doc/isocline-inline.svg) A Haskell wrapper around the [Isocline C library](https://github.com/daanx/isocline#readme) which can provide an alternative to GNU Readline. (The Isocline library is included whole and there are no runtime dependencies).
                 Please see the [readme](https://github.com/daanx/isocline/haskell#readme) on GitHub for more information.
diff --git a/src/completions.c b/src/completions.c
--- a/src/completions.c
+++ b/src/completions.c
@@ -153,12 +153,17 @@
   *arg = cms->completer_arg;
 }
 
-ic_public bool ic_has_completions( ic_completion_env_t* cenv ) {
-  return (cenv->env->completions->count > 0);
+
+ic_public void* ic_completion_arg( const ic_completion_env_t* cenv ) {
+  return (cenv == NULL ? NULL : cenv->env->completions->completer_arg);
 }
 
-ic_public bool ic_stop_completing(ic_completion_env_t* cenv) {
-  return (cenv->env->completions->completer_max <= 0);
+ic_public bool ic_has_completions( const ic_completion_env_t* cenv ) {
+  return (cenv == NULL ? false : cenv->env->completions->count > 0);
+}
+
+ic_public bool ic_stop_completing( const ic_completion_env_t* cenv) {
+  return (cenv == NULL ? true : cenv->env->completions->completer_max <= 0);
 }