diff --git a/detekt-api/src/main/kotlin/io/gitlab/arturbosch/detekt/api/Rule.kt b/detekt-api/src/main/kotlin/io/gitlab/arturbosch/detekt/api/Rule.kt
index 22a32cd51dc..0783904c49a 100644
--- a/detekt-api/src/main/kotlin/io/gitlab/arturbosch/detekt/api/Rule.kt
+++ b/detekt-api/src/main/kotlin/io/gitlab/arturbosch/detekt/api/Rule.kt
@@ -72,7 +72,7 @@ abstract class Rule(
     private fun computeSeverity(): SeverityLevel {
         val configValue: String = valueOrNull(SEVERITY_KEY)
             ?: ruleSetConfig.valueOrDefault(SEVERITY_KEY, "warning")
-        return enumValueOf(configValue.toUpperCase(Locale.US))
+        return enumValueOf(configValue.uppercase(Locale.US))
     }
 
     /**
diff --git a/detekt-generator/src/main/kotlin/io/gitlab/arturbosch/detekt/generator/DetektPrinter.kt b/detekt-generator/src/main/kotlin/io/gitlab/arturbosch/detekt/generator/DetektPrinter.kt
index a9dbb1e11f8..c257551d4ec 100644
--- a/detekt-generator/src/main/kotlin/io/gitlab/arturbosch/detekt/generator/DetektPrinter.kt
+++ b/detekt-generator/src/main/kotlin/io/gitlab/arturbosch/detekt/generator/DetektPrinter.kt
@@ -42,7 +42,7 @@ class DetektPrinter(private val arguments: GeneratorArgs) {
         check(ruleSet.length > 1) { "Rule set name must be not empty or less than two symbols." }
         return """
             |---
-            |title: ${ruleSet[0].toUpperCase()}${ruleSet.substring(1)} Rule Set
+            |title: ${ruleSet[0].uppercaseChar()}${ruleSet.substring(1)} Rule Set
             |sidebar: home_sidebar
             |keywords: [rules, $ruleSet]
             |permalink: $ruleSet.html
diff --git a/detekt-report-html/src/main/kotlin/io/github/detekt/report/html/HtmlOutputReport.kt b/detekt-report-html/src/main/kotlin/io/github/detekt/report/html/HtmlOutputReport.kt
index 930c97001bf..26b093f44d6 100644
--- a/detekt-report-html/src/main/kotlin/io/github/detekt/report/html/HtmlOutputReport.kt
+++ b/detekt-report-html/src/main/kotlin/io/github/detekt/report/html/HtmlOutputReport.kt
@@ -123,7 +123,7 @@ class HtmlOutputReport : OutputReport() {
                 span("description") { text(findings.first().issue.description) }
             }
 
-            a("$DETEKT_WEBSITE_BASE_URL/docs/rules/${group.toLowerCase(Locale.US)}#${rule.toLowerCase(Locale.US)}") {
+            a("$DETEKT_WEBSITE_BASE_URL/docs/rules/${group.lowercase(Locale.US)}#${rule.lowercase(Locale.US)}") {
                 +"Documentation"
             }
 
diff --git a/detekt-report-md/src/main/kotlin/io/github/detekt/report/md/MdOutputReport.kt b/detekt-report-md/src/main/kotlin/io/github/detekt/report/md/MdOutputReport.kt
index 45fed53e3c0..fbbad99188c 100644
--- a/detekt-report-md/src/main/kotlin/io/github/detekt/report/md/MdOutputReport.kt
+++ b/detekt-report-md/src/main/kotlin/io/github/detekt/report/md/MdOutputReport.kt
@@ -97,7 +97,7 @@ private fun MarkdownContent.renderRule(rule: String, group: String, findings: Li
     paragraph {
         link(
             "Documentation",
-            "$DETEKT_WEBSITE_BASE_URL/docs/rules/${group.toLowerCase(Locale.US)}#${rule.toLowerCase(Locale.US)}"
+            "$DETEKT_WEBSITE_BASE_URL/docs/rules/${group.lowercase(Locale.US)}#${rule.lowercase(Locale.US)}"
         )
     }
 
diff --git a/detekt-report-sarif/src/main/kotlin/io/github/detekt/report/sarif/RuleDescriptors.kt b/detekt-report-sarif/src/main/kotlin/io/github/detekt/report/sarif/RuleDescriptors.kt
index 90a5348494a..8cb40605522 100644
--- a/detekt-report-sarif/src/main/kotlin/io/github/detekt/report/sarif/RuleDescriptors.kt
+++ b/detekt-report-sarif/src/main/kotlin/io/github/detekt/report/sarif/RuleDescriptors.kt
@@ -36,8 +36,8 @@ private fun MultiRule.toDescriptors(ruleSetId: RuleSetId): List<ReportingDescrip
     this.rules.map { it.toDescriptor(ruleSetId) }
 
 private fun Rule.toDescriptor(ruleSetId: RuleSetId): ReportingDescriptor {
-    val formattedRuleSetId = ruleSetId.toLowerCase(Locale.US)
-    val formattedRuleId = ruleId.toLowerCase(Locale.US)
+    val formattedRuleSetId = ruleSetId.lowercase(Locale.US)
+    val formattedRuleId = ruleId.lowercase(Locale.US)
 
     return ReportingDescriptor(
         id = "detekt.$ruleSetId.$ruleId",
diff --git a/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlEscape.kt b/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlEscape.kt
index d1dc122cbb3..7ccff352b15 100644
--- a/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlEscape.kt
+++ b/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlEscape.kt
@@ -276,7 +276,7 @@ private object Xml10EscapeSymbolsInitializer {
     }
 
     private operator fun ByteArray.set(c: Char, value: Byte) {
-        set(c.toInt(), value)
+        set(c.code, value)
     }
 
     /**
diff --git a/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlOutputReport.kt b/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlOutputReport.kt
index 9c8c31f9efe..0258b16ed9b 100644
--- a/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlOutputReport.kt
+++ b/detekt-report-xml/src/main/kotlin/io/github/detekt/report/xml/XmlOutputReport.kt
@@ -17,7 +17,7 @@ class XmlOutputReport : OutputReport() {
     override val name = "Checkstyle XML report"
 
     private val Finding.severityLabel: String
-        get() = severity.name.toLowerCase(Locale.US)
+        get() = severity.name.lowercase(Locale.US)
 
     override fun render(detektion: Detektion): String {
         val smells = detektion.findings.flatMap { it.value }
diff --git a/detekt-report-xml/src/test/kotlin/io/github/detekt/report/xml/XmlOutputFormatSpec.kt b/detekt-report-xml/src/test/kotlin/io/github/detekt/report/xml/XmlOutputFormatSpec.kt
index d88ebab00ed..0580e662b21 100644
--- a/detekt-report-xml/src/test/kotlin/io/github/detekt/report/xml/XmlOutputFormatSpec.kt
+++ b/detekt-report-xml/src/test/kotlin/io/github/detekt/report/xml/XmlOutputFormatSpec.kt
@@ -188,7 +188,7 @@ class XmlOutputFormatSpec {
         @ParameterizedTest
         @EnumSource(SeverityLevel::class)
         fun `renders detektion with severity as XML with severity`(severity: SeverityLevel) {
-            val xmlSeverity = severity.name.toLowerCase(Locale.US)
+            val xmlSeverity = severity.name.lowercase(Locale.US)
             val finding = object : CodeSmell(
                 issue = Issue("issue_id", Severity.CodeSmell, "issue description", Debt.FIVE_MINS),
                 entity = entity1,
diff --git a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MagicNumber.kt b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MagicNumber.kt
index 0e5356914a8..afd031a840f 100644
--- a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MagicNumber.kt
+++ b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MagicNumber.kt
@@ -178,7 +178,7 @@ class MagicNumber(config: Config = Config.empty) : Rule(config) {
 
     private fun normalizeForParsingAsDouble(text: String): String {
         return text.trim()
-            .toLowerCase(Locale.US)
+            .lowercase(Locale.US)
             .replace("_", "")
             .removeSuffix("l")
             .removeSuffix("d")
diff --git a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnderscoresInNumericLiterals.kt b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnderscoresInNumericLiterals.kt
index 86669eaccd4..a6ef5bb8b5d 100644
--- a/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnderscoresInNumericLiterals.kt
+++ b/detekt-rules-style/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/UnderscoresInNumericLiterals.kt
@@ -105,7 +105,7 @@ class UnderscoresInNumericLiterals(config: Config = Config.empty) : Rule(config)
 
     private fun normalizeForMatching(text: String): String {
         return text.trim()
-            .toLowerCase(Locale.ROOT)
+            .lowercase(Locale.ROOT)
             .removeSuffix("l")
             .removeSuffix("d")
             .removeSuffix("f")