diff --git a/src/ascii_poly.c b/src/ascii_poly.c
index 4c54077..4b245b6 100644
--- a/src/ascii_poly.c
+++ b/src/ascii_poly.c
@@ -397,7 +397,7 @@ poly_to_base64(fmpz_poly_t poly,
 	result_string->ptr = base64_string;
 	result_string->len = strlen(base64_string);
 
-	free(string_rep);
+	string_delete(string_rep);
 	free(tmp);
 
 	return result_string;
diff --git a/src/keypair.c b/src/keypair.c
index f47c056..b5eb052 100644
--- a/src/keypair.c
+++ b/src/keypair.c
@@ -121,6 +121,7 @@ export_priv_key(char const * const filename,
 	priv_string = poly_to_base64(priv_u, ctx);
 	write_file(priv_string, filename);
 
+	fmpz_poly_clear(priv_u);
 	string_delete(priv_string);
 }
 
@@ -145,7 +146,7 @@ import_public_key(char const * const filename,
 	fmpz_poly_set(pub, **imported);
 
 	string_delete(pub_string);
-	poly_delete(**imported);
+	poly_delete_array(imported);
 	free(imported);
 }
 
@@ -185,7 +186,7 @@ import_priv_key(char const * const filename,
 
 cleanup:
 	string_delete(pub_string);
-	poly_delete(**imported);
+	poly_delete_array(imported);
 	free(imported);
 }
 
diff --git a/src/poly.c b/src/poly.c
index beb8180..481051e 100644
--- a/src/poly.c
+++ b/src/poly.c
@@ -117,10 +117,13 @@ poly_delete_array(fmpz_poly_t **poly_array)
 
 	while(poly_array[i]) {
 		poly_delete(*(poly_array[i]));
-		free(*(poly_array[i]));
+		free(poly_array[i]);
 		i++;
 	}
-	free(poly_array);
+
+	/* avoid double free */
+	if (i > 1)
+		free(poly_array);
 }
 
 /*------------------------------------------------------------------------*/