diff --git a/compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KtFirCompositeScope.fir.txt b/compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KtFirCompositeScope.fir.txt
index 7b4e9decf37..ccfb90227b4 100644
--- a/compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KtFirCompositeScope.fir.txt
+++ b/compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KtFirCompositeScope.fir.txt
@@ -20,7 +20,7 @@ FILE: KtFirCompositeScope.kt
         public final fun getAllNames(): R|kotlin/collections/Set<kotlin/String>| {
             ^getAllNames R|/withValidityAssertion|<R|kotlin/collections/Set<kotlin/String>|>(<L> = withValidityAssertion@fun <anonymous>(): R|kotlin/collections/Set<kotlin/String>| <inline=Inline, kind=UNKNOWN>  {
                 ^ R|/buildSet|<R|kotlin/String|>(<L> = buildSet@fun R|kotlin/collections/MutableSet<kotlin/String>|.<anonymous>(): R|kotlin/Unit| <inline=Inline, kind=UNKNOWN>  {
-                    this@R|/KtFirCompositeScope|.R|/KtFirCompositeScope.subScopes|.R|kotlin/collections/flatMapTo|<R|KtScope|, R|kotlin/String|, R|kotlin/collections/MutableSet<Stub (builder inference): TypeVariable(E)>|>(this@R|special/anonymous|, <L> = flatMapTo@fun <anonymous>(it: R|KtScope|): R|kotlin/collections/Iterable<kotlin/String>| <inline=Inline, kind=UNKNOWN>  {
+                    this@R|/KtFirCompositeScope|.R|/KtFirCompositeScope.subScopes|.R|kotlin/collections/flatMapTo|<R|KtScope|, R|kotlin/String|, R|kotlin/collections/MutableSet<kotlin/String>|>(this@R|special/anonymous|, <L> = flatMapTo@fun <anonymous>(it: R|KtScope|): R|kotlin/collections/Iterable<kotlin/String>| <inline=Inline, kind=UNKNOWN>  {
                         ^ R|<local>/it|.R|/KtScope.getAllNames|()
                     }
                     )
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirBuilderInferenceSession.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirBuilderInferenceSession.kt
index f5461eb2fb9..eb487c7e9d0 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirBuilderInferenceSession.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirBuilderInferenceSession.kt
@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.fir.expressions.FirResolvable
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.resolve.calls.Candidate
 import org.jetbrains.kotlin.fir.resolve.calls.ResolutionContext
+import org.jetbrains.kotlin.fir.resolve.inference.model.ConeBuilderInferenceSubstitutionConstraintPosition
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirDefaultTransformer
@@ -21,13 +22,12 @@ import org.jetbrains.kotlin.fir.visitors.transformSingle
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.resolve.calls.inference.buildAbstractResultingSubstitutor
 import org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintSystemCompletionMode
-import org.jetbrains.kotlin.resolve.calls.inference.model.BuilderInferencePosition
-import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintKind
-import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
-import org.jetbrains.kotlin.resolve.calls.inference.model.NewConstraintSystemImpl
+import org.jetbrains.kotlin.resolve.calls.inference.model.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.BUILDER_INFERENCE_ANNOTATION_FQ_NAME
 import org.jetbrains.kotlin.types.model.TypeConstructorMarker
+import org.jetbrains.kotlin.types.model.TypeSubstitutorMarker
 import org.jetbrains.kotlin.types.model.TypeVariableMarker
+import org.jetbrains.kotlin.types.model.safeSubstitute
 
 class FirBuilderInferenceSession(
     private val lambda: FirAnonymousFunction,
@@ -195,10 +195,13 @@ class FirBuilderInferenceSession(
         var introducedConstraint = false
 
         for (initialConstraint in storage.initialConstraints) {
+            if (initialConstraint.position is BuilderInferencePosition) continue
+            val substitutedConstraint = initialConstraint.substitute(callSubstitutor)
+
             val lower =
-                nonFixedToVariablesSubstitutor.substituteOrSelf(callSubstitutor.substituteOrSelf(initialConstraint.a as ConeKotlinType)) // TODO: SUB
+                nonFixedToVariablesSubstitutor.substituteOrSelf(substitutedConstraint.a as ConeKotlinType) // TODO: SUB
             val upper =
-                nonFixedToVariablesSubstitutor.substituteOrSelf(callSubstitutor.substituteOrSelf(initialConstraint.b as ConeKotlinType)) // TODO: SUB
+                nonFixedToVariablesSubstitutor.substituteOrSelf(substitutedConstraint.b as ConeKotlinType) // TODO: SUB
 
             if (commonSystem.isProperType(lower) && commonSystem.isProperType(upper)) continue
 
@@ -207,12 +210,12 @@ class FirBuilderInferenceSession(
             when (initialConstraint.constraintKind) {
                 ConstraintKind.LOWER -> error("LOWER constraint shouldn't be used, please use UPPER")
 
-                ConstraintKind.UPPER -> commonSystem.addSubtypeConstraint(lower, upper, initialConstraint.position)
+                ConstraintKind.UPPER -> commonSystem.addSubtypeConstraint(lower, upper, substitutedConstraint.position)
 
                 ConstraintKind.EQUALITY ->
                     with(commonSystem) {
-                        addSubtypeConstraint(lower, upper, initialConstraint.position)
-                        addSubtypeConstraint(upper, lower, initialConstraint.position)
+                        addSubtypeConstraint(lower, upper, substitutedConstraint.position)
+                        addSubtypeConstraint(upper, lower, substitutedConstraint.position)
                     }
             }
         }
@@ -229,6 +232,20 @@ class FirBuilderInferenceSession(
         return introducedConstraint
     }
 
+    private fun InitialConstraint.substitute(substitutor: TypeSubstitutorMarker): InitialConstraint {
+        val lowerSubstituted = substitutor.safeSubstitute(resolutionContext.typeContext, this.a)
+        val upperSubstituted = substitutor.safeSubstitute(resolutionContext.typeContext, this.b)
+
+        if (lowerSubstituted == a && upperSubstituted == b) return this
+
+        return InitialConstraint(
+            lowerSubstituted,
+            upperSubstituted,
+            this.constraintKind,
+            ConeBuilderInferenceSubstitutionConstraintPosition(this) // TODO
+        )
+    }
+
     private fun updateCalls(commonSystem: NewConstraintSystemImpl) {
         val nonFixedToVariablesSubstitutor = createNonFixedTypeToVariableSubstitutor()
         val commonSystemSubstitutor = commonSystem.buildCurrentSubstitutor() as ConeSubstitutor
diff --git a/compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/inference/model/FirConstraintPositionAndErrors.kt b/compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/inference/model/FirConstraintPositionAndErrors.kt
index 63a64ac05d2..cabc47d18b3 100644
--- a/compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/inference/model/FirConstraintPositionAndErrors.kt
+++ b/compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/inference/model/FirConstraintPositionAndErrors.kt
@@ -28,3 +28,7 @@ class ConeExplicitTypeParameterConstraintPosition(
 class ConeLambdaArgumentConstraintPosition(
     anonymousFunction: FirAnonymousFunction
 ) : LambdaArgumentConstraintPosition<FirAnonymousFunction>(anonymousFunction)
+
+
+class ConeBuilderInferenceSubstitutionConstraintPosition(initialConstraint: InitialConstraint) :
+    BuilderInferenceSubstitutionConstraintPosition<Nothing?, InitialConstraint>(null, initialConstraint) // TODO
\ No newline at end of file