diff --git a/conf/cf-lex.l b/conf/cf-lex.l
index 704a1750..c9d2f5a5 100644
--- a/conf/cf-lex.l
+++ b/conf/cf-lex.l
@@ -255,7 +255,7 @@ WHITE [ \t]
   return IP4;
 }
 
-{XIGIT}{2}(:{XIGIT}{2}|{XIGIT}{2}){15,} {
+{XIGIT}{2}((:{XIGIT}{2}){15,}|({XIGIT}{2}){15,}) {
   char *s = yytext;
   size_t len = 0, i;
   struct bytestring *bytes;
diff --git a/filter/test.conf b/filter/test.conf
index 6a28e4b3..f902f99f 100644
--- a/filter/test.conf
+++ b/filter/test.conf
@@ -335,6 +335,26 @@ ip p;
 	p = 1234:5678::;
 	bt_assert(!p.is_v4);
 	bt_assert(p.mask(24) = 1234:5600::);
+
+	p = 1:2:3:4:5:6:7:8;
+	bt_assert(!p.is_v4);
+	bt_assert(format(p) = "1:2:3:4:5:6:7:8");
+	bt_assert(p.mask(64) = 1:2:3:4::);
+
+	p = 10:20:30:40:50:60:70:80;
+	bt_assert(!p.is_v4);
+	bt_assert(format(p) = "10:20:30:40:50:60:70:80");
+	bt_assert(p.mask(64) = 10:20:30:40::);
+
+	p = 1090:20a0:30b0:40c0:50d0:60e0:70f0:8000;
+	bt_assert(!p.is_v4);
+	bt_assert(format(p) = "1090:20a0:30b0:40c0:50d0:60e0:70f0:8000");
+	bt_assert(p.mask(64) = 1090:20a0:30b0:40c0::);
+
+	p = ::fffe:6:c0c:936d:88c7:35d3;
+	bt_assert(!p.is_v4);
+	bt_assert(format(p) = "::fffe:6:c0c:936d:88c7:35d3");
+	bt_assert(p.mask(64) = 0:0:fffe:6::);
 }
 
 bt_test_suite(t_ip, "Testing ip address");