diff --git a/documentation/operation.md b/documentation/operation.md
index 19f46d6d6..f6ec4cee0 100644
--- a/documentation/operation.md
+++ b/documentation/operation.md
@@ -47,4 +47,4 @@ In general, there are 3 options to start a component:
 
 1. With the build tool (Gradle, Yarn)
 2. Build the source > start the bundle/jar/binary
-3. Build the source > build Docker image > run Docker container
\ No newline at end of file
+3. Build the source > build Docker image > run Docker container
diff --git a/server/zally-core/src/main/kotlin/org/zalando/zally/core/CaseChecker.kt b/server/zally-core/src/main/kotlin/org/zalando/zally/core/CaseChecker.kt
index b3d559f41..f822e3f05 100644
--- a/server/zally-core/src/main/kotlin/org/zalando/zally/core/CaseChecker.kt
+++ b/server/zally-core/src/main/kotlin/org/zalando/zally/core/CaseChecker.kt
@@ -209,7 +209,7 @@ class CaseChecker(
         type: String,
         check: CaseCheck?
     ): List<Violation> = context.api
-        .getAllParameters().values
+        .getAllParameters()
         .filter { type.toLowerCase() == it.`in` }
         .flatMap { param ->
             check("$type parameter", "$type parameters", check, param.name)
diff --git a/server/zally-core/src/main/kotlin/org/zalando/zally/core/util/OpenApiUtil.kt b/server/zally-core/src/main/kotlin/org/zalando/zally/core/util/OpenApiUtil.kt
index a768551f7..0900e6b8d 100644
--- a/server/zally-core/src/main/kotlin/org/zalando/zally/core/util/OpenApiUtil.kt
+++ b/server/zally-core/src/main/kotlin/org/zalando/zally/core/util/OpenApiUtil.kt
@@ -115,11 +115,13 @@ fun OpenAPI.getAllProperties(): Map<String, Schema<Any>> {
  * Returns all defined parameters of an API specification
  * @return a collection of parameters
  */
-fun OpenAPI.getAllParameters(): Map<String, Parameter> = this.components?.parameters.orEmpty() +
-    this.paths.orEmpty().values.flatMap { it?.parameters.orEmpty().mapNotNull { it.name to it } } +
-    this.paths.orEmpty().values.flatMap {
-        it?.readOperations().orEmpty().flatMap { it?.parameters.orEmpty().mapNotNull { it.name to it } }
-    }
+fun OpenAPI.getAllParameters(): Collection<Parameter> =
+    this.components?.parameters?.values.orEmpty().filterNotNull().toList() +
+        this.paths.orEmpty().values.flatMap { it?.parameters.orEmpty().filterNotNull() } +
+        this.paths.orEmpty().values.flatMap {
+            it?.readOperations().orEmpty().flatMap { it?.parameters.orEmpty().filterNotNull() }
+        }
+
 
 fun OpenAPI.getAllSecuritySchemes(): Map<String, SecurityScheme> = this.components?.securitySchemes.orEmpty()
 
diff --git a/server/zally-ruleset-zalando/src/main/kotlin/org/zalando/zally/ruleset/zalando/QueryParameterCollectionFormatRule.kt b/server/zally-ruleset-zalando/src/main/kotlin/org/zalando/zally/ruleset/zalando/QueryParameterCollectionFormatRule.kt
index dd968bf92..6619ee968 100644
--- a/server/zally-ruleset-zalando/src/main/kotlin/org/zalando/zally/ruleset/zalando/QueryParameterCollectionFormatRule.kt
+++ b/server/zally-ruleset-zalando/src/main/kotlin/org/zalando/zally/ruleset/zalando/QueryParameterCollectionFormatRule.kt
@@ -21,7 +21,7 @@ class QueryParameterCollectionFormatRule {
     @Check(severity = Severity.SHOULD)
     fun checkParametersCollectionFormat(context: Context): List<Violation> =
         if (context.isOpenAPI3())
-            context.api.getAllParameters().values
+            context.api.getAllParameters()
                 .filter { "query" == it.`in` && "array" == it.schema?.type }
                 .filter { it.style == null || allowedStyle != it.style }
                 .map { context.violation(description, it) }
diff --git a/server/zally-ruleset-zally/src/main/kotlin/org/zalando/zally/ruleset/zally/PathParameterRule.kt b/server/zally-ruleset-zally/src/main/kotlin/org/zalando/zally/ruleset/zally/PathParameterRule.kt
index 83da258c1..57ef9a191 100644
--- a/server/zally-ruleset-zally/src/main/kotlin/org/zalando/zally/ruleset/zally/PathParameterRule.kt
+++ b/server/zally-ruleset-zally/src/main/kotlin/org/zalando/zally/ruleset/zally/PathParameterRule.kt
@@ -29,7 +29,7 @@ class PathParameterRule {
 
     @Check(severity = Severity.MUST)
     fun checkRequiredPathAttribute(context: Context): List<Violation> =
-        context.api.getAllParameters().map { entry -> entry.value }
+        context.api.getAllParameters()
             .filter { parameter ->
                 parameter.isInPath() && !parameter.required
             }
@@ -42,8 +42,8 @@ class PathParameterRule {
         if (context.isOpenAPI3()) {
             return context.api
                 .getAllParameters()
-                .filterValues { it.schema == null && it.content == null }
-                .map { (_, parameter) ->
+                .filter { it.schema == null && it.content == null }
+                .map { parameter ->
                     context.violation(requiredSchemaOrContentErrorMessage(parameter.name), parameter)
                 }
         }
@@ -54,12 +54,12 @@ class PathParameterRule {
     fun validateParameterContentMapStructure(context: Context): List<Violation> {
         if (context.isOpenAPI3()) {
             return context.api.getAllParameters()
-                .filterValues {
+                .filter {
                     if (it.content != null) {
                         it.content.isEmpty() || it.content.size > 1
                     } else false
                 }
-                .map { (_, parameter) ->
+                .map { parameter ->
                     context.violation(contentMapStructureErrorMessage(parameter.name), parameter)
                 }
         }