diff --git a/centvrion/ast_nodes.py b/centvrion/ast_nodes.py
index 2439fe0..7e497f7 100644
--- a/centvrion/ast_nodes.py
+++ b/centvrion/ast_nodes.py
@@ -418,9 +418,14 @@ class BinOp(Node):
           return vtable, ValNul()
         return vtable, ValInt((lv or 0) + (rv or 0))
       case "SYMBOL_COLON":
-        lv = lv if lv is not None else ""
-        rv = rv if rv is not None else ""
-        return vtable, ValStr(lv + rv)
+        magnvm = "MAGNVM" in vtable["#modules"]
+        svbnvlla = "SVBNVLLA" in vtable["#modules"]
+        def _coerce(v):
+          if v is None: return ""
+          if isinstance(v, bool): return "VERITAS" if v else "FALSITAS"
+          if isinstance(v, int): return int_to_num(v, magnvm, svbnvlla)
+          return v
+        return vtable, ValStr(_coerce(lv) + _coerce(rv))
       case "SYMBOL_MINUS":
         return vtable, ValInt((lv or 0) - (rv or 0))
       case "SYMBOL_TIMES":
diff --git a/tests.py b/tests.py
index 6605d6c..f51ff7e 100644
--- a/tests.py
+++ b/tests.py
@@ -611,6 +611,9 @@ string_concat_tests = [
   ('NVLLVS : "hello"', Program([], [ExpressionStatement(BinOp(Nullus(), String("hello"), "SYMBOL_COLON"))]), ValStr("hello")),
   ('"hello" : NVLLVS', Program([], [ExpressionStatement(BinOp(String("hello"), Nullus(), "SYMBOL_COLON"))]), ValStr("hello")),
   ('NVLLVS : NVLLVS', Program([], [ExpressionStatement(BinOp(Nullus(), Nullus(), "SYMBOL_COLON"))]), ValStr("")),
+  # integers coerce to Roman numerals in string context
+  ('"value: " : V', Program([], [ExpressionStatement(BinOp(String("value: "), Numeral("V"), "SYMBOL_COLON"))]), ValStr("value: V")),
+  ('X : " items"', Program([], [ExpressionStatement(BinOp(Numeral("X"), String(" items"), "SYMBOL_COLON"))]), ValStr("X items")),
 ]
 
 class TestStringConcat(unittest.TestCase):