diff --git a/.gitignore b/.gitignore
index c5903368f..d6c4af4e3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,5 +18,3 @@ out/
 # Generated by javac -h and runtime
 *.class
 *.log
-
-/kmath-ejml/src/main/kotlin/space/kscience/kmath/ejml/_generated.kt
diff --git a/examples/src/main/kotlin/space/kscience/kmath/structures/buffers.kt b/examples/src/main/kotlin/space/kscience/kmath/structures/buffers.kt
index eabb16701..0f7fdc46a 100644
--- a/examples/src/main/kotlin/space/kscience/kmath/structures/buffers.kt
+++ b/examples/src/main/kotlin/space/kscience/kmath/structures/buffers.kt
@@ -19,4 +19,4 @@ fun main() {
     with(DoubleField.bufferAlgebra(5)) {
         println(number(2.0) + produce(1, 2, 3, 4, 5))
     }
-}
\ No newline at end of file
+}
diff --git a/kmath-optimization/build.gradle.kts b/kmath-optimization/build.gradle.kts
index ca013b2f4..68b82ad65 100644
--- a/kmath-optimization/build.gradle.kts
+++ b/kmath-optimization/build.gradle.kts
@@ -17,4 +17,4 @@ kotlin.sourceSets {
 
 readme {
     maturity = ru.mipt.npm.gradle.Maturity.EXPERIMENTAL
-}
\ No newline at end of file
+}
diff --git a/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationBuilder.kt b/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationBuilder.kt
index 10a25c029..416d0195d 100644
--- a/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationBuilder.kt
+++ b/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationBuilder.kt
@@ -11,7 +11,7 @@ import space.kscience.kmath.expressions.Symbol
 import space.kscience.kmath.misc.FeatureSet
 
 public abstract class OptimizationBuilder<T, R : OptimizationProblem<T>> {
-    public val features: ArrayList<OptimizationFeature> = ArrayList()
+    public val features: MutableList<OptimizationFeature> = ArrayList()
 
     public fun addFeature(feature: OptimizationFeature) {
         features.add(feature)