diff --git a/include/lsof.h b/include/lsof.h
index 277e1af7..30ee16e6 100644
--- a/include/lsof.h
+++ b/include/lsof.h
@@ -572,6 +572,8 @@ enum lsof_error lsof_gather(struct lsof_context *ctx,
  * You should call `lsof_free_result` to free all `struct lsof_result`
  * before destroying the context.
  *
+ * ctx may be NULL.
+ *
  * You must not use the context anymore after this call.
  *
  * \since API version 1
@@ -579,6 +581,8 @@ enum lsof_error lsof_gather(struct lsof_context *ctx,
 void lsof_destroy(struct lsof_context *ctx);
 
 /** Free struct lsof_result
+ *
+ * result may be NULL.
  *
  * \since API version 1
  */
diff --git a/lib/lsof.c b/lib/lsof.c
index af4b04fd..cc60c7c4 100644
--- a/lib/lsof.c
+++ b/lib/lsof.c
@@ -732,6 +732,9 @@ void lsof_free_result(struct lsof_result *result) {
     int pi, fi;
     struct lsof_process *p;
     struct lsof_file *f;
+    if (!result) {
+        return;
+    }
     for (pi = 0; pi < result->num_processes; pi++) {
         p = &result->processes[pi];
         /* Free files */