diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
index 2f923b921c6..f37ce1bde4e 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
@@ -102,7 +102,10 @@ public fun getParamDescriptors(fromDescriptor: DeclarationDescriptor): List<Decl
         is ClassifierDescriptor -> {
             val typeParams = fromDescriptor.getTypeConstructor().getParameters()
             if (fromDescriptor is ClassDescriptor) {
-                return typeParams + fromDescriptor.getUnsubstitutedPrimaryConstructor().getValueParameters()
+                val constructorDescriptor = fromDescriptor.getUnsubstitutedPrimaryConstructor()
+                if (constructorDescriptor != null) {
+                    return typeParams + constructorDescriptor.getValueParameters()
+                }
             }
             return typeParams
         }