diff --git a/lib/comp.c b/lib/comp.c
index 6f1f891..1d41481 100644
--- a/lib/comp.c
+++ b/lib/comp.c
@@ -2548,7 +2548,7 @@ static int compile_class (hcl_t* hcl, hcl_cnode_t* src)
 	}
 
 	tmp = HCL_CNODE_CONS_CAR(obj);
-	if (/*HCL_CNODE_IS_COLON(tmp) || */HCL_CNODE_IS_DBLCOLONS(tmp))
+	if (HCL_CNODE_IS_COLON(tmp)) /* check for superclass marker */
 	{
 		hcl_cnode_t* marker;
 
diff --git a/lib/read.c b/lib/read.c
index 4b212b2..9f91279 100644
--- a/lib/read.c
+++ b/lib/read.c
@@ -893,6 +893,13 @@ static HCL_INLINE int can_colon_list (hcl_t* hcl)
 	if (rstl->count <= 0) return 0; /* not allowed at the list beginning  */
 
 	/* mark the state that a colon has appeared in the list */
+	if (HCL_CNODE_IS_TYPED(HCL_CNODE_CONS_CAR(rstl->head), HCL_CNODE_CLASS))
+	{
+		/* class :superclassame ...
+		 * class name:superclassname ... */
+		return 2;
+	}
+
 	if (rstl->count == 1) rstl->flagv |= JSON; /* mark that the first key is colon-delimited */
 	else if (!(rstl->flagv & JSON))
 	{
@@ -945,7 +952,14 @@ static HCL_INLINE int can_colon_list (hcl_t* hcl)
 		/* ugly dual use of a colon sign. switch to MLIST if the first element
 		 * is delimited by a colon. e.g. (obj:new 10 20 30)  */
 		tmp = HCL_CNODE_CONS_CAR(rstl->head);
-		if (!HCL_CNODE_IS_FOR_DATA(tmp)) return 0;
+		if (!HCL_CNODE_IS_FOR_DATA(tmp))
+		{
+			/* check if the first element can refer to or represent an object.
+			 * for example, '#[1 2 3]:at 1' is proper message send.
+			 * while 'class:xxx {}' is not a method call. it is unamed class
+			 * that inherits from xxx */
+			return 0;
+		}
 
 		LIST_FLAG_SET_CONCODE(rstl->flagv, HCL_CONCODE_MLIST);
 		rstl->flagv &= ~JSON;
diff --git a/t/class-5001.err b/t/class-5001.err
index b403103..5e3bc6c 100644
--- a/t/class-5001.err
+++ b/t/class-5001.err
@@ -36,18 +36,18 @@ class super.a [ a ] { ##ERROR: syntax error - invalid class name 'super.a' for '
 
 ---
 
-class a :: 20 { ##ERROR: syntax error - invalid superclass name '20' after '::' for 'class'
+class a: 20 { ##ERROR: syntax error - invalid superclass name '20' after ':' for 'class'
 }
 
 ---
 
-class a :: class { ##ERROR: syntax error - invalid superclass name 'class' after '::' for 'class'
+class a: class { ##ERROR: syntax error - invalid superclass name 'class' after ':' for 'class'
 
 }
 
 ---
 
-class a :: #(1 2) { ##ERROR: syntax error - no valid superclass name after '::' for 'class'
+class a: #(1 2) { ##ERROR: syntax error - no valid superclass name after ':' for 'class'
 }
 
 ---
@@ -81,7 +81,7 @@ class B [ x y ] {
 
 };
 
-class X :: B [ a b ] {
+class X: B [ a b ] {
 	fun(#ci) new(t) {
 		| a |
 		set self.a t;
@@ -231,3 +231,16 @@ class a {
 	fun() { ##ERROR: syntax error - unnamed function defined with 'fun' prohibited in class initialziation context
 	}
 }
+
+---
+
+class X10 [ x ] {
+     fun(#ci) make() { x := 1234; return self; };
+     fun get-x() { return x };
+}
+
+X11 := (class:X10 {
+})
+
+class X11 { ##ERROR: exception not handled - "prohibited redefintion of X11"
+}
diff --git a/t/insta-01.hcl b/t/insta-01.hcl
index b2be6f9..14b10de 100644
--- a/t/insta-01.hcl
+++ b/t/insta-01.hcl
@@ -26,7 +26,7 @@ class A [ a b c ]  {
 	fun get-c() { return self.c; };
 };
 
-class B :: A [ d e f ] {
+class B: A [ d e f ] {
 
 	fun(#ci) newInstance(x y z) {
 		super:newInstance (* x 2) (* y 2) (* z 2);
diff --git a/t/insta-02.hcl b/t/insta-02.hcl
index 91e4d41..8098a9e 100644
--- a/t/insta-02.hcl
+++ b/t/insta-02.hcl
@@ -31,11 +31,12 @@ else { printf "OK: t is %d\n" t };
 j := #{ ((X:make):get-x): 9999, 4512: ((X: make): get-x) };
 v := (dic.get j 1234);
 if (nqv? v 9999) { printf "ERROR: v is not 9999\n" } \
-else {  printf "OK:  value is %d\n" v };
+else {  printf "OK: value is %d\n" v };
 
 v := (dic.get j 4512);
 if (nqv? v 1234) { printf "ERROR: v is not 1234\n" } \
-else { printf "OK:  value is %d\n" v };
+else { printf "OK: value is %d\n" v };
+
 
 ## --------------------------------------------------------------
 
@@ -58,11 +59,11 @@ class X0 [ a b c d ] {
 
 }; a := (X0:new); v := (a:x)
 if (nqv? v 100) { printf "ERROR: v is not 100\n" } \
-else { printf "OK:  value is %d\n" v }
+else { printf "OK: value is %d\n" v }
 
 v := ((a:y) 20);
 if (nqv? v 21) { printf "ERROR: v is not 21\n" } \
-else { printf "OK:  value is %d\n" v }
+else { printf "OK: value is %d\n" v }
 
 ## --------------------------------------------------------------
 
@@ -92,15 +93,15 @@ fun X1:get_a() {
 
 v := ((X1:new):get_a)
 if (nqv? v 20) { printf "ERROR: v is not 20 - %d\n" v } \
-else { printf "OK:  value is %d\n" v }
+else { printf "OK: value is %d\n" v }
 
 v := (((X1:new):make 5 6 7):get_j)
 if (nqv? v 79) { printf "ERROR: v is not 79 - %d\n" v } \
-else { printf "OK:  value is %d\n" v }
+else { printf "OK: value is %d\n" v }
 
 v := (((X1:new):make 6 6 7):get_j)
 if (nqv? v 70) { printf "ERROR: v is not 70 - %d\n" v } \
-else { printf "OK:  value is %d\n" v }
+else { printf "OK: value is %d\n" v }
 
 ## --------------------------------------------------------------
 
@@ -175,3 +176,17 @@ else { printf "OK: value is %d\n" v }
 v := { X5:t; (X6:t) + 10 }
 if (nqv? v 50) { printf "ERROR: v is not 50 - %d\n" v } \
 else { printf "OK: value is %d\n" v }
+
+## --------------------------------------------------------------
+class X10 [ x ] {
+	fun(#ci) make() { x := 1234; return self; };
+	fun get-x() { return x };
+}
+
+X11 := (class:X10 {
+})
+
+v := (X11:make)
+v := (v:get-x)
+if (== v 1234) { printf "OK: v is %d\n" v } \
+else {printf "ERROR: v is %d, not 1234\n" v }