diff --git a/build.gradle.kts b/build.gradle.kts
index df9a318..f675dc9 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,13 +1,3 @@
-val versions = mapOf(
-        "httpcore" to "5.2.3",
-        "httpclient" to "5.2.1",
-        "jackson" to "2.16.0",
-        "slf4j" to "1.7.36",
-        "junit-jupiter" to "5.8.2",
-        "mockito" to "4.5.1",
-        "assertj" to "3.22.0"
-)
-
 allprojects {
     group = "com.github.ok2c.hc5"
     version = "0.3.1-SNAPSHOT"
@@ -17,7 +7,6 @@ allprojects {
     }
 
     extra["releaseVersion"] = !version.toString().endsWith("-SNAPSHOT")
-    extra["versions"] = versions
 }
 
 subprojects {
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
new file mode 100644
index 0000000..5a137eb
--- /dev/null
+++ b/gradle/libs.versions.toml
@@ -0,0 +1,20 @@
+[versions]
+httpcore = "5.2.3"
+jackson = "2.16.0"
+httpclient = "5.2.1"
+slf4j = "1.7.36"
+junit = "5.8.2"
+mockito = "4.5.1"
+assertj = "3.22.0"
+
+
+[libraries]
+httpcore = { group = "org.apache.httpcomponents.core5", name = "httpcore5", version.ref = "httpcore" }
+httpcore-h2 = { group = "org.apache.httpcomponents.core5", name = "httpcore5-h2", version.ref = "httpcore" }
+jackson-databind = { group = "com.fasterxml.jackson.core", name = "jackson-databind", version.ref = "jackson" }
+httpclient = { group = "org.apache.httpcomponents.client5", name = "httpclient5", version.ref = "httpclient" }
+slf4j-simple = { group = "org.slf4j", name = "slf4j-simple", version.ref = "slf4j" }
+junit-engine = { group = "org.junit.jupiter", name = "junit-jupiter-engine", version.ref = "junit" }
+junit-params = { group = "org.junit.jupiter", name = "junit-jupiter-params", version.ref = "junit" }
+assertj-core = { group = "org.assertj", name = "assertj-core", version.ref = "assertj" }
+mockito = { group = "org.mockito", name = "mockito-inline", version.ref = "mockito" }
diff --git a/hc5-async-json/build.gradle.kts b/hc5-async-json/build.gradle.kts
index cb70f8b..a9b3464 100644
--- a/hc5-async-json/build.gradle.kts
+++ b/hc5-async-json/build.gradle.kts
@@ -12,19 +12,18 @@ java {
     withSourcesJar()
 }
 
-val versions: Map<String, String> by project.extra
 val releaseVersion: Boolean by project.extra
 
 dependencies {
-    api("org.apache.httpcomponents.core5:httpcore5:${versions["httpcore"]}")
-    api("org.apache.httpcomponents.core5:httpcore5-h2:${versions["httpcore"]}")
-    api("com.fasterxml.jackson.core:jackson-databind:${versions["jackson"]}")
-    testImplementation("org.apache.httpcomponents.client5:httpclient5:${versions["httpclient"]}")
-    testImplementation("org.junit.jupiter:junit-jupiter-engine:${versions["junit-jupiter"]}")
-    testImplementation("org.junit.jupiter:junit-jupiter-params:${versions["junit-jupiter"]}")
-    testImplementation("org.assertj:assertj-core:${versions["assertj"]}")
-    testImplementation("org.slf4j:slf4j-simple:${versions["slf4j"]}")
-    testImplementation("org.mockito:mockito-inline:${versions["mockito"]}")
+    api(libs.httpcore)
+    api(libs.httpcore.h2)
+    api(libs.jackson.databind)
+    testImplementation(libs.httpclient)
+    testImplementation(libs.slf4j.simple)
+    testImplementation(libs.junit.engine)
+    testImplementation(libs.junit.params)
+    testImplementation(libs.mockito)
+    testImplementation(libs.assertj.core)
 }
 
 tasks.named<Test>("test") {