diff --git a/CHANGES b/CHANGES
index 55eafd9..8dfc771 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,10 +1,11 @@
 1.3 (2021-XX-XX)
     - Change versioning from X.Y.Z to Y.Z
-    - the repository file hierachy has been reorganized (compat/ include/)
-    - man page has been extended
-    - large portions of code have been reformatted to adhere to OpenBSD's source
+    - The repository file hierachy has been reorganized (compat/ include/)
+    - Man page has been extended
+    - Large portions of code have been reformatted to adhere to OpenBSD's source
       file style guide to improve readability.
-    - refactor: replace two-dimensional array for ASN storage with Red-Black tree
+    - Refactor: replace two-dimensional array for ASN storage with Red-Black tree
+    - Reduced memory usage
 
 0.0.9 (2021-08-18)
     - Fix various memory errors
diff --git a/expander.c b/expander.c
index da4ac2e..df2be34 100644
--- a/expander.c
+++ b/expander.c
@@ -446,7 +446,7 @@ bgpq_expander_invalidate_asn(struct bgpq_expander *b, const char *q)
 			sx_report(SX_ERROR, "overflow: %s\n", q);
 			return;
 		}
-		if (asn >= 4294967295) {
+		if (asn == 0 || asn >= 4294967295) {
 			sx_report(SX_ERROR, "out of range: %s\n", q);
 			return;
 		}
@@ -456,15 +456,10 @@ bgpq_expander_invalidate_asn(struct bgpq_expander *b, const char *q)
 		}
 
 		find.asn = asn;
-		res = RB_FIND(asn_tree, &b->asnlist, &find);
-		if (res == NULL)
-			return;
-
-		if (RB_REMOVE(asn_tree, &b->asnlist, res) == NULL) {
-			sx_report(SX_ERROR, "failed to remove: %lu", asn);
-			return;
+		if ((res = RB_FIND(asn_tree, &b->asnlist, &find)) == NULL) {
+			RB_REMOVE(asn_tree, &b->asnlist, res);
+			free(res);
 		}
-			
 	}
 }