diff --git a/docs/mutable-utils/styles/jetbrains-mono.css b/docs/mutable-utils/styles/jetbrains-mono.css
deleted file mode 100644
index 9a0f06f..0000000
--- a/docs/mutable-utils/styles/jetbrains-mono.css
+++ /dev/null
@@ -1,17 +0,0 @@
-@font-face{
-    font-family: 'JetBrains Mono';
-    src: url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/web/JetBrainsMono-Regular.eot') format('embedded-opentype'),
-         url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/webfonts/JetBrainsMono-Regular.woff2') format('woff2'),
-         url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/ttf/JetBrainsMono-Regular.ttf') format('truetype');
-    font-weight: normal;
-    font-style: normal;
-}
-
-@font-face{
-    font-family: 'JetBrains Mono';
-    src: url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/web/JetBrainsMono-Bold.eot') format('embedded-opentype'),
-         url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/webfonts/JetBrainsMono-Bold.woff2') format('woff2'),
-         url('https://raw.githubusercontent.com/JetBrains/JetBrainsMono/master/fonts/ttf/JetBrainsMono-Bold.ttf') format('truetype');
-    font-weight: bold;
-    font-style: bold;
-}
\ No newline at end of file
diff --git a/kopykat-ksp/src/main/kotlin/at/kopyk/CopyConstructors.kt b/kopykat-ksp/src/main/kotlin/at/kopyk/CopyConstructors.kt
index 40175bd..47e3a41 100644
--- a/kopykat-ksp/src/main/kotlin/at/kopyk/CopyConstructors.kt
+++ b/kopykat-ksp/src/main/kotlin/at/kopyk/CopyConstructors.kt
@@ -11,6 +11,7 @@ import at.kopyk.utils.fullName
 import at.kopyk.utils.getPrimaryConstructorProperties
 import at.kopyk.utils.lang.takeIfInstanceOf
 import at.kopyk.utils.minimal
+import at.kopyk.utils.sanitizedName
 import com.google.devtools.ksp.getVisibility
 import com.google.devtools.ksp.symbol.KSAnnotated
 import com.google.devtools.ksp.symbol.KSAnnotation
@@ -75,7 +76,7 @@ private fun TypeCompileScope.copyConstructorFileSpec(
           to.properties.toList().zipByName(from.getAllProperties().toList()) { to, from ->
             propertyDefinition(others, from, to)
           }.filterNotNull()
-        addReturn("${to.baseName}(${propertyAssignments.joinToString()})")
+        addReturn("${to.sanitizedName}(${propertyAssignments.joinToString()})")
       }
     }
   }
@@ -94,10 +95,10 @@ private fun propertyDefinition(
 ): String? {
   val fromType = from.typeDeclaration
   val toType = to.typeDeclaration
-  val propertyName = from.baseName
+  val propertyName = from.sanitizedName
   return when {
     fromType == null || toType == null -> null
-    others.hasCopyConstructor(fromType, toType) -> "$propertyName = ${toType.baseName}(from.$propertyName)"
+    others.hasCopyConstructor(fromType, toType) -> "$propertyName = ${toType.sanitizedName}(from.$propertyName)"
     else -> "$propertyName = from.$propertyName"
   }
 }
diff --git a/kopykat-ksp/src/main/kotlin/at/kopyk/CopyMap.kt b/kopykat-ksp/src/main/kotlin/at/kopyk/CopyMap.kt
index 66e773a..75a71f7 100644
--- a/kopykat-ksp/src/main/kotlin/at/kopyk/CopyMap.kt
+++ b/kopykat-ksp/src/main/kotlin/at/kopyk/CopyMap.kt
@@ -14,6 +14,7 @@ import at.kopyk.utils.fullName
 import at.kopyk.utils.lang.joinWithWhen
 import at.kopyk.utils.lang.mapRun
 import at.kopyk.utils.lang.onEachRun
+import at.kopyk.utils.sanitizedName
 import at.kopyk.utils.typeCategory
 import com.squareup.kotlinpoet.FileSpec
 import com.squareup.kotlinpoet.ksp.toKModifier
@@ -33,7 +34,7 @@ internal val TypeCompileScope.copyMapFunctionKt: FileSpec
               defaultValue = "{ it }",
             )
           }
-          .mapRun { "$baseName = $baseName(this, this.$baseName)" }
+          .mapRun { "$sanitizedName = $sanitizedName(this, this.$sanitizedName)" }
           .run { addReturn(repeatOnSubclasses(joinToString(), "copy")) }
       }
     }
diff --git a/kopykat-ksp/src/main/kotlin/at/kopyk/MutableCopy.kt b/kopykat-ksp/src/main/kotlin/at/kopyk/MutableCopy.kt
index 0cacc17..ffe3d12 100644
--- a/kopykat-ksp/src/main/kotlin/at/kopyk/MutableCopy.kt
+++ b/kopykat-ksp/src/main/kotlin/at/kopyk/MutableCopy.kt
@@ -24,15 +24,20 @@ import at.kopyk.utils.lang.forEachRun
 import at.kopyk.utils.lang.joinWithWhen
 import at.kopyk.utils.mutable
 import at.kopyk.utils.onKnownCategory
+import at.kopyk.utils.sanitizedName
 import at.kopyk.utils.typeCategory
+import com.squareup.kotlinpoet.ClassName
 import com.squareup.kotlinpoet.FileSpec
 import com.squareup.kotlinpoet.FunSpec
 import com.squareup.kotlinpoet.KModifier
+import com.squareup.kotlinpoet.ParameterizedTypeName
+import com.squareup.kotlinpoet.TypeName
 import com.squareup.kotlinpoet.ksp.toKModifier
 
 internal val TypeCompileScope.mutableCopyKt: FileSpec
   get() =
     buildFile(target.mutable.reflectionName()) {
+      addImports()
       addGeneratedMarker()
       addDslMarkerClass()
       addMutableCopy()
@@ -45,6 +50,31 @@ internal val TypeCompileScope.mutableCopyKt: FileSpec
       }
     }
 
+internal fun FileCompilerScope.addImports() {
+  with(element) {
+    val targetPkg = target.packageName
+    mutationInfo.forEach { (declaration, mutationInfo) ->
+      if (declaration.type.resolve().hasMutableCopy()) {
+        mutationInfo.className.usedPackages.forEach { propertyPkg ->
+          if (propertyPkg != targetPkg) {
+            file.addImport(propertyPkg, "freeze", "toMutable")
+          }
+        }
+      }
+    }
+  }
+}
+
+@Suppress("RecursivePropertyAccessor")
+internal val TypeName.usedPackages: Set<String>
+  get() =
+    when (this) {
+      is ClassName -> setOf(this.packageName)
+      is ParameterizedTypeName ->
+        this.rawType.usedPackages + this.typeArguments.flatMap { it.usedPackages }
+      else -> emptySet()
+    }
+
 internal fun FileCompilerScope.addMutableCopy() {
   with(element) {
     file.addClass(target.mutable) {
@@ -117,10 +147,10 @@ internal fun FileCompilerScope.addCopyClosure() {
 private fun FileCompilerScope.addRetrofittedCopyFunction() {
   with(element) {
     addCopyFunction {
-      properties.forEachRun { addParameter(name = baseName, type = typeName, defaultValue = "this.$baseName") }
+      properties.forEachRun { addParameter(name = baseName, type = typeName, defaultValue = "this.$sanitizedName") }
       addReturn(
         sealedTypes.joinWithWhen { type ->
-          "is ${type.fullName} -> this.copy(${properties.joinToString { "${it.baseName} = ${it.baseName}" }})"
+          "is ${type.fullName} -> this.copy(${properties.joinToString { "${it.sanitizedName} = ${it.sanitizedName}" }})"
         },
       )
     }
diff --git a/kopykat-ksp/src/main/kotlin/at/kopyk/utils/KspExtensions.kt b/kopykat-ksp/src/main/kotlin/at/kopyk/utils/KspExtensions.kt
index d3f1662..59b8c89 100644
--- a/kopykat-ksp/src/main/kotlin/at/kopyk/utils/KspExtensions.kt
+++ b/kopykat-ksp/src/main/kotlin/at/kopyk/utils/KspExtensions.kt
@@ -6,7 +6,10 @@ import com.google.devtools.ksp.symbol.KSDeclarationContainer
 import com.google.devtools.ksp.symbol.KSPropertyDeclaration
 
 internal val KSDeclaration.baseName: String
-  get() = simpleName.asString().sanitize()
+  get() = simpleName.asString()
+
+internal val KSDeclaration.sanitizedName: String
+  get() = baseName.sanitize()
 
 internal val KSDeclaration.fullName: String
   get() = qualifiedName?.asString() ?: simpleName.asString()
@@ -36,10 +39,13 @@ private fun KSClassDeclaration.hasPrimaryProperty(property: KSPropertyDeclaratio
 /**
  * Sanitizes each delimited section if it matches with Kotlin reserved keywords.
  */
-private fun String.sanitize(
+internal fun String.sanitize(
   delimiter: String = ".",
   prefix: String = "",
-) = splitToSequence(delimiter).joinToString(delimiter, prefix) { if (it in KOTLIN_KEYWORDS) "`$it`" else it }
+): String =
+  splitToSequence(delimiter).joinToString(delimiter, prefix) {
+    if (it in KOTLIN_KEYWORDS) "`$it`" else it
+  }
 
 private val KOTLIN_KEYWORDS =
   setOf(
diff --git a/kopykat-ksp/src/main/kotlin/at/kopyk/utils/TypeCompileScope.kt b/kopykat-ksp/src/main/kotlin/at/kopyk/utils/TypeCompileScope.kt
index 9cd4a00..bc4d8c6 100644
--- a/kopykat-ksp/src/main/kotlin/at/kopyk/utils/TypeCompileScope.kt
+++ b/kopykat-ksp/src/main/kotlin/at/kopyk/utils/TypeCompileScope.kt
@@ -57,7 +57,7 @@ internal sealed interface TypeCompileScope : KSDeclaration, LoggerScope {
   fun KSPropertyDeclaration.toAssignment(
     wrapper: (String) -> String,
     source: String? = null,
-  ): String = "$baseName = ${wrapper("${source ?: ""}$baseName")}"
+  ): String = "$sanitizedName = ${wrapper("${source ?: ""}$sanitizedName")}"
 
   fun Sequence<Pair<KSPropertyDeclaration, MutationInfo<TypeName>>>.joinAsAssignmentsWithMutation(
     wrapper: MutationInfo<TypeName>.(String) -> String,
diff --git a/kopykat-ksp/src/test/kotlin/at/kopyk/CopyMapTest.kt b/kopykat-ksp/src/test/kotlin/at/kopyk/CopyMapTest.kt
index aea0287..b6dcab3 100644
--- a/kopykat-ksp/src/test/kotlin/at/kopyk/CopyMapTest.kt
+++ b/kopykat-ksp/src/test/kotlin/at/kopyk/CopyMapTest.kt
@@ -163,4 +163,15 @@ class CopyMapTest {
       |val r = p2.second
       """.evals("r" to 2)
   }
+
+  @Test
+  fun `keyword as fields, issue #93`() {
+    """
+      |data class Person(val `in`: String, val `out`: Int)
+      |
+      |val p1 = Person("Alex", 1)
+      |val p2 = p1.copyMap(`out` = { it + 1 })
+      |val r = p2.`out`
+      """.evals("r" to 2)
+  }
 }
diff --git a/kopykat-ksp/src/test/kotlin/at/kopyk/MutableCopyTest.kt b/kopykat-ksp/src/test/kotlin/at/kopyk/MutableCopyTest.kt
index a3929aa..2d463ae 100644
--- a/kopykat-ksp/src/test/kotlin/at/kopyk/MutableCopyTest.kt
+++ b/kopykat-ksp/src/test/kotlin/at/kopyk/MutableCopyTest.kt
@@ -224,4 +224,15 @@ class MutableCopyTest {
       |val r = p2.d
       """.evals("r" to listOf("e", "f"))
   }
+
+  @Test
+  fun `keyword as fields, issue #93`() {
+    """
+    |data class Person(val `in`: String, val `out`: Int)
+    |
+    |val p1 = Person("Alex", 1)
+    |val p2 = p1.copy { `out` = `out` + 1 }
+    |val r = p2.`out`
+    """.evals("r" to 2)
+  }
 }