diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt
index ab8ec7c..2c158c5 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt
@@ -142,15 +142,19 @@ open class Obj {
      * @param calledFromLyng true if called from Lyng's `toString`. Normally this parameter should be ignored,
      *      but it is used to avoid endless recursion in [Obj.toString] base implementation
      */
-    open suspend fun toString(scope: Scope,calledFromLyng: Boolean=false): ObjString {
-        return if (this is ObjString) this
-        else if( !calledFromLyng ) {
-            invokeInstanceMethod(scope, "toString") {
-                ObjString(this.toString())
+    open suspend fun toString(scope: Scope, calledFromLyng: Boolean = false): ObjString {
+        if (this is ObjString) return this
+        return if (!calledFromLyng) {
+            invokeInstanceMethod(scope, "toString", Arguments.EMPTY) {
+                defaultToString(scope)
             } as ObjString
-        } else { ObjString(this.toString()) }
+        } else {
+            defaultToString(scope)
+        }
     }
 
+    open suspend fun defaultToString(scope: Scope): ObjString = ObjString(this.toString())
+
     /**
      * Class of the object: definition of member functions (top-level), etc.
      * Note that using lazy allows to avoid endless recursion here
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjException.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjException.kt
index 372bcf5..e65a5a3 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjException.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjException.kt
@@ -89,7 +89,7 @@ open class ObjException(
 
     override val objClass: ObjClass = exceptionClass
 
-    override suspend fun toString(scope: Scope, calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         val at = getStackTrace().list.firstOrNull()?.toString(scope)
             ?: ObjString("(unknown)")
         return ObjString("${objClass.className}: $message at $at")
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstance.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstance.kt
index 0fe857a..15dcd24 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstance.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstance.kt
@@ -187,16 +187,16 @@ class ObjInstance(override val objClass: ObjClass) : Obj() {
             !it.key.contains("::") && it.value.visibility.isPublic && it.value.type.serializable
         }
 
-    override suspend fun toString(scope: Scope, calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         return ObjString(buildString {
-                append("${objClass.className}(")
-                var first = true
-                for ((name, value) in publicFields) {
-                    if (first) first = false else append(",")
-                    append("$name=${value.value.toString(scope)}")
-                }
-                append(")")
-            })
+            append("${objClass.className}(")
+            var first = true
+            for ((name, value) in publicFields) {
+                if (first) first = false else append(",")
+                append("$name=${value.value.toString(scope)}")
+            }
+            append(")")
+        })
     }
 
     override suspend fun inspect(scope: Scope): String {
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstanceClass.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstanceClass.kt
index 3597766..3f211d4 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstanceClass.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstanceClass.kt
@@ -43,7 +43,7 @@ class ObjInstanceClass(val name: String, vararg parents: ObjClass) : ObjClass(na
 
     init {
         addFn("toString", true) {
-            ObjString(thisObj.toString())
+            thisObj.toString(this, true)
         }
     }
 
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjList.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjList.kt
index 216cbdd..909d60d 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjList.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjList.kt
@@ -198,7 +198,7 @@ class ObjList(val list: MutableList<Obj> = mutableListOf()) : Obj() {
         return JsonArray(list.map { it.toJson(scope) })
     }
 
-    override suspend fun toString(scope: Scope, calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         return ObjString(buildString {
             append("[")
             var first = true
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMap.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMap.kt
index 55db28e..55bbbe7 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMap.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMap.kt
@@ -52,7 +52,7 @@ class ObjMapEntry(val key: Obj, val value: Obj) : Obj() {
         else -> scope.raiseIndexOutOfBounds()
     }
 
-    override suspend fun toString(scope: Scope, calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         return ObjString("(${key.toString(scope).value} => ${value.toString(scope).value})")
     }
 
@@ -124,7 +124,7 @@ class ObjMap(val map: MutableMap<Obj, Obj> = mutableMapOf()) : Obj() {
         return -1
     }
 
-    override suspend fun toString(scope: Scope, calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         val reusult = buildString {
             append("Map(")
             var first = true
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRange.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRange.kt
index 3f782c0..6bc7e59 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRange.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRange.kt
@@ -29,7 +29,7 @@ class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Ob
 
     override val objClass: ObjClass = type
 
-    override suspend fun toString(scope: Scope,calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         val result = StringBuilder()
         result.append("${start?.inspect(scope) ?: '∞'} ..")
         if (!isEndInclusive) result.append('<')
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRegex.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRegex.kt
index b9b5033..aed2ef0 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRegex.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRegex.kt
@@ -103,7 +103,7 @@ class ObjRegexMatch(val match: MatchResult) : Obj() {
         )
     }
 
-    override suspend fun toString(scope: Scope,calledFromLyng: Boolean): ObjString {
+    override suspend fun defaultToString(scope: Scope): ObjString {
         return ObjString("RegexMath(${objRange.toString(scope)},${objGroups.toString(scope)})")
     }
 
diff --git a/lynglib/src/commonTest/kotlin/ScriptTest.kt b/lynglib/src/commonTest/kotlin/ScriptTest.kt
index 9523945..60bd8b1 100644
--- a/lynglib/src/commonTest/kotlin/ScriptTest.kt
+++ b/lynglib/src/commonTest/kotlin/ScriptTest.kt
@@ -4311,6 +4311,28 @@ class ScriptTest {
         """.trimIndent())
     }
 
+    @Test
+    fun testCustomToStringBug() = runTest {
+        eval("""
+            class A(x,y)
+            class B(x,y) {
+                fun toString() {
+                    "B(%d,%d)"(x,y)
+                }
+            }
+            
+            assertEquals("B(1,2)", B(1,2).toString())
+            assertEquals("A(x=1,y=2)", A(1,2).toString())
+            
+            // now tricky part: this _should_ cakk custom toString()
+            assertEquals(":B(1,2)", ":" + B(1,2).toString())
+            // and this must be exactly same:
+            assertEquals(":B(1,2)", ":" + B(1,2))
+            
+        """.trimIndent())
+
+    }
+
 
 //    @Test
 //    fun testSplatAssignemnt() = runTest {