diff --git a/include/xo/reader/define_xs.hpp b/include/xo/reader/define_xs.hpp
index 3a740a32..bee7d24f 100644
--- a/include/xo/reader/define_xs.hpp
+++ b/include/xo/reader/define_xs.hpp
@@ -60,7 +60,8 @@ namespace xo {
             virtual void on_typedescr(TypeDescr td,
                                       exprstatestack * /*p_stack*/,
                                       rp<Expression> * /*p_emit_expr*/) override;
-            virtual void on_colon(exprstatestack * p_stack) override;
+            virtual void on_colon_token(const token_type & tk,
+                                        exprstatestack * p_stack) override;
             virtual void on_semicolon(exprstatestack * p_stack,
                                       rp<Expression> * /*p_emit_expr*/) override;
             virtual void on_singleassign(exprstatestack * p_stack) override;
diff --git a/include/xo/reader/exprstate.hpp b/include/xo/reader/exprstate.hpp
index 6e2f5481..2f0c9e6a 100644
--- a/include/xo/reader/exprstate.hpp
+++ b/include/xo/reader/exprstate.hpp
@@ -131,7 +131,9 @@ namespace xo {
             virtual void on_symbol_token(const token_type & tk,
                                          exprstatestack * p_stack,
                                          rp<Expression> * p_emit_expr);
-            virtual void on_colon(exprstatestack * p_stack);
+            /** handle incoming ':' token **/
+            virtual void on_colon_token(const token_type & tk,
+                                        exprstatestack * p_stack);
             virtual void on_semicolon(exprstatestack * p_stack,
                                       rp<Expression> * p_emit_expr);
             virtual void on_singleassign(exprstatestack * p_stack);
diff --git a/include/xo/reader/paren_xs.hpp b/include/xo/reader/paren_xs.hpp
index 964b8dc3..fa63f212 100644
--- a/include/xo/reader/paren_xs.hpp
+++ b/include/xo/reader/paren_xs.hpp
@@ -56,7 +56,8 @@ namespace xo {
             virtual void on_symbol_token(const token_type & tk,
                                          exprstatestack * p_stack,
                                          rp<Expression> * p_emit_expr) override;
-            virtual void on_colon(exprstatestack * p_stack) override;
+            virtual void on_colon_token(const token_type & tk,
+                                        exprstatestack * p_stack) override;
             virtual void on_semicolon(exprstatestack * p_stack,
                                       rp<Expression> * /*p_emit_expr*/) override;
             virtual void on_singleassign(exprstatestack * p_stack) override;
diff --git a/include/xo/reader/progress_xs.hpp b/include/xo/reader/progress_xs.hpp
index 7d6a25f1..e0e2c7db 100644
--- a/include/xo/reader/progress_xs.hpp
+++ b/include/xo/reader/progress_xs.hpp
@@ -43,7 +43,8 @@ namespace xo {
             virtual void on_typedescr(TypeDescr td,
                                       exprstatestack * /*p_stack*/,
                                       rp<Expression> * /*p_emit_expr*/) override;
-            virtual void on_colon(exprstatestack * p_stack) override;
+            virtual void on_colon_token(const token_type & tk,
+                                        exprstatestack * p_stack) override;
             virtual void on_semicolon(exprstatestack * p_stack,
                                       rp<Expression> * /*p_emit_expr*/) override;
             virtual void on_singleassign(exprstatestack * p_stack) override;
diff --git a/src/reader/define_xs.cpp b/src/reader/define_xs.cpp
index 5ecb82f5..82081331 100644
--- a/src/reader/define_xs.cpp
+++ b/src/reader/define_xs.cpp
@@ -326,7 +326,9 @@ namespace xo {
         }
 
         void
-        define_xs::on_colon(exprstatestack * p_stack) {
+        define_xs::on_colon_token(const token_type & /*tk*/,
+                                  exprstatestack * p_stack)
+        {
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
diff --git a/src/reader/exprstate.cpp b/src/reader/exprstate.cpp
index b83cad6a..bb8c1a18 100644
--- a/src/reader/exprstate.cpp
+++ b/src/reader/exprstate.cpp
@@ -504,7 +504,9 @@ namespace xo {
         }
 
         void
-        exprstate::on_colon(exprstatestack * /*p_stack*/) {
+        exprstate::on_colon_token(const token_type & /*tk*/,
+                                  exprstatestack * /*p_stack*/)
+        {
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
@@ -686,7 +688,7 @@ namespace xo {
                 return;
 
             case tokentype::tk_colon:
-                this->on_colon(p_stack);
+                this->on_colon_token(tk, p_stack);
                 return;
 
             case tokentype::tk_doublecolon:
diff --git a/src/reader/paren_xs.cpp b/src/reader/paren_xs.cpp
index f9ed033c..ebc07527 100644
--- a/src/reader/paren_xs.cpp
+++ b/src/reader/paren_xs.cpp
@@ -108,7 +108,8 @@ namespace xo {
         }
 
         void
-        paren_xs::on_colon(exprstatestack * /*p_stack*/)
+        paren_xs::on_colon_token(const token_type & /*tk*/,
+                                 exprstatestack * /*p_stack*/)
         {
             constexpr const char * c_self_name = "paren_xs::on_colon";
 
diff --git a/src/reader/progress_xs.cpp b/src/reader/progress_xs.cpp
index 7ac56de5..32964064 100644
--- a/src/reader/progress_xs.cpp
+++ b/src/reader/progress_xs.cpp
@@ -82,7 +82,9 @@ namespace xo {
         }
 
         void
-        progress_xs::on_colon(exprstatestack * /*p_stack*/) {
+        progress_xs::on_colon_token(const token_type & /*tk*/,
+                                    exprstatestack * /*p_stack*/)
+        {
             constexpr const char * self_name = "progress_xs::on_colon";
 
             throw std::runtime_error(tostr(self_name,