diff --git a/lib/ofdm_mapper.cc b/lib/ofdm_mapper.cc
index 62dffe2..ebf0175 100644
--- a/lib/ofdm_mapper.cc
+++ b/lib/ofdm_mapper.cc
@@ -157,6 +157,7 @@ int general_work(int noutput, gr_vector_int& ninput_items,
 	if(d_symbols_offset == d_symbols_len) {
 		d_symbols_offset = 0;
 		free(d_symbols);
+		d_symbols = 0;
 	}
 
 	return i;