diff --git a/plugins/filter_alter_size/alter_size.c b/plugins/filter_alter_size/alter_size.c
index e4f5693ea2b..75e50052bf3 100644
--- a/plugins/filter_alter_size/alter_size.c
+++ b/plugins/filter_alter_size/alter_size.c
@@ -51,6 +51,8 @@ static int cb_alter_size_init(struct flb_filter_instance *ins,
     if (ctx->log_decoder == NULL) {
         flb_plg_error(ins, "could not initialize event decoder");
 
+        flb_free(ctx);
+
         return -1;
     }
 
@@ -58,7 +60,9 @@ static int cb_alter_size_init(struct flb_filter_instance *ins,
 
     if (ctx->log_encoder == NULL) {
         flb_plg_error(ins, "could not initialize event encoder");
+
         flb_log_event_decoder_destroy(ctx->log_decoder);
+        flb_free(ctx);
 
         return -1;
     }