diff --git a/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/AbbreviatedTypeAttribute.kt b/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/AbbreviatedTypeAttribute.kt
index 4ce57340329..5d0cbf56d4b 100644
--- a/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/AbbreviatedTypeAttribute.kt
+++ b/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/AbbreviatedTypeAttribute.kt
@@ -12,7 +12,7 @@ class AbbreviatedTypeAttribute(
 ) : ConeAttribute<AbbreviatedTypeAttribute>() {
     override fun union(other: AbbreviatedTypeAttribute?): AbbreviatedTypeAttribute? = null
     override fun intersect(other: AbbreviatedTypeAttribute?): AbbreviatedTypeAttribute? = null
-    override fun add(other: AbbreviatedTypeAttribute?): AbbreviatedTypeAttribute? = null
+    override fun add(other: AbbreviatedTypeAttribute?): AbbreviatedTypeAttribute = other ?: this
     override fun isSubtypeOf(other: AbbreviatedTypeAttribute?): Boolean = true
     override fun toString(): String = "{${coneType.renderForDebugging()}=}"