diff --git a/plugin/build.gradle.kts b/plugin/build.gradle.kts
index 503cd6e..ed44674 100644
--- a/plugin/build.gradle.kts
+++ b/plugin/build.gradle.kts
@@ -30,7 +30,6 @@ dependencies {
     compileOnly("org.gradle:gradle-tooling-api:${gradle.gradleVersion}")
     implementation("org.apache.maven:maven-model:latest.release")
     implementation("org.apache.maven:maven-model-builder:latest.release")
-    implementation("com.squareup.okio:okio:latest.release")
 
     compatTestImplementation(embeddedKotlin("stdlib-jdk8"))
     compatTestImplementation(embeddedKotlin("test-junit5"))
diff --git a/plugin/gradle/dependency-locks/compileClasspath.lockfile b/plugin/gradle/dependency-locks/compileClasspath.lockfile
index 4dba989..9505418 100644
--- a/plugin/gradle/dependency-locks/compileClasspath.lockfile
+++ b/plugin/gradle/dependency-locks/compileClasspath.lockfile
@@ -1,7 +1,6 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.squareup.okio:okio:2.2.2
 org.apache.commons:commons-lang3:3.8.1
 org.apache.maven:maven-artifact:3.6.1
 org.apache.maven:maven-builder-support:3.6.1
diff --git a/plugin/gradle/dependency-locks/runtimeClasspath.lockfile b/plugin/gradle/dependency-locks/runtimeClasspath.lockfile
index 7351deb..771fe58 100644
--- a/plugin/gradle/dependency-locks/runtimeClasspath.lockfile
+++ b/plugin/gradle/dependency-locks/runtimeClasspath.lockfile
@@ -1,7 +1,6 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.squareup.okio:okio:2.2.2
 org.apache.commons:commons-lang3:3.8.1
 org.apache.maven:maven-artifact:3.6.1
 org.apache.maven:maven-builder-support:3.6.1
@@ -10,6 +9,3 @@ org.apache.maven:maven-model:3.6.1
 org.codehaus.plexus:plexus-component-annotations:1.7.1
 org.codehaus.plexus:plexus-interpolation:1.25
 org.codehaus.plexus:plexus-utils:3.2.0
-org.jetbrains.kotlin:kotlin-stdlib-common:1.2.60
-org.jetbrains.kotlin:kotlin-stdlib:1.2.60
-org.jetbrains:annotations:13.0
diff --git a/plugin/gradle/dependency-locks/testCompileClasspath.lockfile b/plugin/gradle/dependency-locks/testCompileClasspath.lockfile
index 98e2984..b250c16 100644
--- a/plugin/gradle/dependency-locks/testCompileClasspath.lockfile
+++ b/plugin/gradle/dependency-locks/testCompileClasspath.lockfile
@@ -1,7 +1,6 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.squareup.okio:okio:2.2.2
 org.apache.commons:commons-lang3:3.8.1
 org.apache.maven:maven-artifact:3.6.1
 org.apache.maven:maven-builder-support:3.6.1
diff --git a/plugin/gradle/dependency-locks/testRuntimeClasspath.lockfile b/plugin/gradle/dependency-locks/testRuntimeClasspath.lockfile
index 98e2984..b250c16 100644
--- a/plugin/gradle/dependency-locks/testRuntimeClasspath.lockfile
+++ b/plugin/gradle/dependency-locks/testRuntimeClasspath.lockfile
@@ -1,7 +1,6 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.squareup.okio:okio:2.2.2
 org.apache.commons:commons-lang3:3.8.1
 org.apache.maven:maven-artifact:3.6.1
 org.apache.maven:maven-builder-support:3.6.1
diff --git a/plugin/src/main/kotlin/org/nixos/gradle2nix/DependencyResolver.kt b/plugin/src/main/kotlin/org/nixos/gradle2nix/DependencyResolver.kt
index 37498c0..654dd9b 100644
--- a/plugin/src/main/kotlin/org/nixos/gradle2nix/DependencyResolver.kt
+++ b/plugin/src/main/kotlin/org/nixos/gradle2nix/DependencyResolver.kt
@@ -1,6 +1,5 @@
 package org.nixos.gradle2nix
 
-import okio.*
 import org.apache.maven.model.Parent
 import org.apache.maven.model.Repository
 import org.apache.maven.model.building.DefaultModelBuilderFactory
@@ -21,6 +20,7 @@ import org.gradle.maven.MavenPomArtifact
 import java.io.File
 import java.io.InputStream
 import java.net.URI
+import java.security.MessageDigest
 
 internal class DependencyResolver(
     private val configurations: ConfigurationContainer,
@@ -153,11 +153,14 @@ private class MavenPomResolver(
     override fun addRepository(repository: Repository, replace: Boolean) {}
 }
 
-private fun sha256(file: File): String {
-    val hashSource = HashingSource.sha256(file.source())
-    val hash: ByteString = hashSource.buffer().use { source ->
-        source.readAll(blackholeSink())
-        hashSource.hash
-    }
-    return hash.base64()
+private val HEX = "0123456789ABCDEF"
+
+private fun sha256(file: File): String = buildString {
+    MessageDigest.getInstance("SHA-256").digest(file.readBytes())
+        .asSequence()
+        .map { it.toInt() }
+        .forEach {
+            append(HEX[it shr 4 and 0x0f])
+            append(HEX[it and 0x0f])
+        }
 }
diff --git a/plugin/src/main/kotlin/org/nixos/gradle2nix/Gradle2NixPlugin.kt b/plugin/src/main/kotlin/org/nixos/gradle2nix/Gradle2NixPlugin.kt
index ad90491..d4c12da 100644
--- a/plugin/src/main/kotlin/org/nixos/gradle2nix/Gradle2NixPlugin.kt
+++ b/plugin/src/main/kotlin/org/nixos/gradle2nix/Gradle2NixPlugin.kt
@@ -1,7 +1,5 @@
 package org.nixos.gradle2nix
 
-import okio.buffer
-import okio.source
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.artifacts.dsl.RepositoryHandler
@@ -140,9 +138,7 @@ private fun Project.projectDependencies(explicitConfigurations: List<String>): D
 private fun fetchDistSha256(url: String): String {
     return URL("$url.sha256").openConnection().run {
         connect()
-        getInputStream().source().buffer().use { source ->
-            source.readUtf8()
-        }
+        getInputStream().reader().use { it.readText() }
     }
 }