diff --git a/SKIE/acceptance-tests b/SKIE/acceptance-tests
index 56ec4dc8..d07f141f 160000
--- a/SKIE/acceptance-tests
+++ b/SKIE/acceptance-tests
@@ -1 +1 @@
-Subproject commit 56ec4dc88ec50f72fa1eadffa2d254bcc84841c4
+Subproject commit d07f141f913bbc3728b9780a8cd5574f02f3a1c4
diff --git a/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirFunction.kt b/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirFunction.kt
index 1d2c8adb..4c4b6e2f 100644
--- a/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirFunction.kt
+++ b/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirFunction.kt
@@ -1,6 +1,7 @@
 package co.touchlab.skie.sir.element
 
 import co.touchlab.skie.sir.signature.Signature
+import co.touchlab.skie.util.collisionFreeIdentifier
 import co.touchlab.skie.util.swift.escapeSwiftIdentifier
 import io.outfoxx.swiftpoet.CodeBlock
 import io.outfoxx.swiftpoet.FunctionSpec
@@ -76,4 +77,31 @@ fun SirFunction.copyValueParametersFrom(valueParameters: List<SirValueParameter>
             inout = it.inout,
         )
     }
+
+    fixValueParameterCollisions()
+}
+
+fun SirFunction.fixValueParameterCollisions() {
+    fixValueParameterNameCollisions()
+    fixValueParameterLabelCollisions()
+}
+
+private fun SirFunction.fixValueParameterNameCollisions() {
+    val usedNames = mutableSetOf<String>()
+
+    valueParameters.forEach { parameter ->
+        parameter.name = parameter.name.collisionFreeIdentifier(usedNames)
+
+        usedNames.add(parameter.name)
+    }
+}
+
+private fun SirFunction.fixValueParameterLabelCollisions() {
+    val usedNames = mutableSetOf<String>()
+
+    valueParameters.forEach { parameter ->
+        parameter.label = parameter.labelOrName.collisionFreeIdentifier(usedNames)
+
+        usedNames.add(parameter.labelOrName)
+    }
 }
diff --git a/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirTypeParameterParent.kt b/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirTypeParameterParent.kt
index c3fbd0fa..44ac8d8d 100644
--- a/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirTypeParameterParent.kt
+++ b/SKIE/kotlin-compiler/core/src/commonMain/kotlin/co/touchlab/skie/sir/element/SirTypeParameterParent.kt
@@ -13,12 +13,28 @@ sealed interface SirTypeParameterParent {
     }
 }
 
-fun SirTypeParameterParent.copyTypeParametersFrom(other: SirClass) {
-    val copiesWithOriginal = other.typeParameters.map {
+fun SirTypeParameterParent.copyTypeParametersFrom(other: SirTypeParameterParent) {
+    copyTypeParametersFrom(other.typeParameters)
+}
+
+fun SirTypeParameterParent.copyTypeParametersFrom(
+    copiedTypeParameters: List<SirTypeParameter>,
+    allTypeParameters: List<SirTypeParameter> = copiedTypeParameters,
+) {
+    val copiesWithOriginal = copiedTypeParameters.map {
         it to SirTypeParameter(it.name)
     }
 
-    val substitutions = copiesWithOriginal.toMap()
+    val nonCopiedTypeParameters = allTypeParameters - copiedTypeParameters.toSet()
+
+    val nonCopiedSubstitutions = nonCopiedTypeParameters.map { nonCopiedTypeParameter ->
+        val existingTypeParameter = (typeParameters.firstOrNull { it.name == nonCopiedTypeParameter.name }
+            ?: error("Type parameter ${nonCopiedTypeParameter.name} not found in parent scope"))
+
+        nonCopiedTypeParameter to existingTypeParameter
+    }
+
+    val substitutions = (copiesWithOriginal + nonCopiedSubstitutions).toMap()
 
     copiesWithOriginal.forEach { (original, copy) ->
         // TODO This is not entirely correct, because we don't substitute type parameters from parent scope as nested scopes are not implemented yet.