diff --git a/xo-reader2/include/xo/reader2/ParserStateMachine.hpp b/xo-reader2/include/xo/reader2/ParserStateMachine.hpp
index fbef2393..31b664c0 100644
--- a/xo-reader2/include/xo/reader2/ParserStateMachine.hpp
+++ b/xo-reader2/include/xo/reader2/ParserStateMachine.hpp
@@ -105,6 +105,9 @@ namespace xo {
             /** operate state machine for incoming if-token @p tk **/
             void on_if_token(const Token & tk);
 
+            /** operate state machine for incoming colon-token @p tk **/
+            void on_colon_token(const Token & tk);
+
             ///@}
 
             /** @defgroup scm-parserstatemachine-error-entrypoints error entry points **/
diff --git a/xo-reader2/src/reader2/DDefineSsm.cpp b/xo-reader2/src/reader2/DDefineSsm.cpp
index 13b99028..8941a20d 100644
--- a/xo-reader2/src/reader2/DDefineSsm.cpp
+++ b/xo-reader2/src/reader2/DDefineSsm.cpp
@@ -477,7 +477,7 @@ namespace xo {
         DDefineSsm::on_def_token(const Token & tk,
                                  ParserStateMachine * p_psm)
         {
-            if (this->defstate_ == defexprstatetype::def_0) {
+            if (defstate_ == defexprstatetype::def_0) {
                 this->defstate_ = defexprstatetype::def_1;
 
                 DExpectSymbolSsm::start(p_psm->parser_alloc(), p_psm);
@@ -502,6 +502,13 @@ namespace xo {
         DDefineSsm::on_colon_token(const Token & tk,
                                    ParserStateMachine * p_psm)
         {
+            if (defstate_ == defexprstatetype::def_2) {
+                this->defstate_ = defexprstatetype::def_3;
+
+                // expect_type_xs::start(p_psm);
+                return;
+            }
+
             p_psm->illegal_input_on_token("DDefineSsm::on_colon_token",
                                           tk,
                                           this->get_expect_str());
diff --git a/xo-reader2/src/reader2/ParserStateMachine.cpp b/xo-reader2/src/reader2/ParserStateMachine.cpp
index ca8bba8b..5c9cc413 100644
--- a/xo-reader2/src/reader2/ParserStateMachine.cpp
+++ b/xo-reader2/src/reader2/ParserStateMachine.cpp
@@ -139,6 +139,10 @@ namespace xo {
                 this->on_if_token(tk);
                 break;
 
+            case tokentype::tk_colon:
+                this->on_colon_token(tk);
+                break;
+
             // all the not-yet handled cases
             case tokentype::tk_invalid:
             case tokentype::tk_bool:
@@ -157,7 +161,6 @@ namespace xo {
             case tokentype::tk_greatequal:
             case tokentype::tk_dot:
             case tokentype::tk_comma:
-            case tokentype::tk_colon:
             case tokentype::tk_doublecolon:
             case tokentype::tk_semicolon:
             case tokentype::tk_singleassign:
@@ -208,6 +211,14 @@ namespace xo {
             stack_->top().on_if_token(tk, this);
         }
 
+        void
+        ParserStateMachine::on_colon_token(const Token & tk)
+        {
+            scope log(XO_DEBUG(debug_flag_), xtag("tk", tk));
+
+            stack_->top().on_colon_token(tk, this);
+        }
+
         void
         ParserStateMachine::capture_error(std::string_view ssm_name,
                                           const DString * errmsg)
diff --git a/xo-reader2/utest/SchematikaParser.test.cpp b/xo-reader2/utest/SchematikaParser.test.cpp
index 8cccfd7b..4e4b778f 100644
--- a/xo-reader2/utest/SchematikaParser.test.cpp
+++ b/xo-reader2/utest/SchematikaParser.test.cpp
@@ -112,6 +112,17 @@ namespace xo {
                 log && log(xtag("result", result));
             }
 
+            {
+                auto & result = parser.on_token(Token::colon_token());
+
+                REQUIRE(parser.has_incomplete_expr() == true);
+                REQUIRE(result.is_incomplete());
+
+                log && log("after colon token:");
+                log && log(xtag("parser", &parser));
+                log && log(xtag("result", result));
+            }
+
             // define-expressions not properly implemented
 
             //REQUIRE(result.error_description());
diff --git a/xo-tokenizer2/include/xo/tokenizer2/Token.hpp b/xo-tokenizer2/include/xo/tokenizer2/Token.hpp
index 7ed490cc..fc448106 100644
--- a/xo-tokenizer2/include/xo/tokenizer2/Token.hpp
+++ b/xo-tokenizer2/include/xo/tokenizer2/Token.hpp
@@ -108,7 +108,7 @@ namespace xo {
             /** token representing comma @c "," **/
             static Token comma() { return Token(tokentype::tk_comma); }
             /** token representing colon @c ":" **/
-            static Token colon() { return Token(tokentype::tk_colon); }
+            static Token colon_token() { return Token(tokentype::tk_colon); }
             /** token representing double-colo @c "::" **/
             static Token doublecolon() { return Token(tokentype::tk_doublecolon); }
             /** token representing semicolon @c ";" **/