diff --git a/docs/build.gradle b/docs/build.gradle
index 0f06812393..bb40a510c1 100644
--- a/docs/build.gradle
+++ b/docs/build.gradle
@@ -23,7 +23,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -91,3 +97,8 @@ Object callback = {
 
 tasks.dokkaGfm(callback)
 tasks.dokkaHtml(callback)
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
diff --git a/tgbotapi.api/build.gradle b/tgbotapi.api/build.gradle
index 54888411ac..32ab4c3861 100644
--- a/tgbotapi.api/build.gradle
+++ b/tgbotapi.api/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -43,8 +49,7 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
diff --git a/tgbotapi.behaviour_builder.fsm/build.gradle b/tgbotapi.behaviour_builder.fsm/build.gradle
index 285b417626..f2c13d81aa 100644
--- a/tgbotapi.behaviour_builder.fsm/build.gradle
+++ b/tgbotapi.behaviour_builder.fsm/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -44,7 +50,6 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
diff --git a/tgbotapi.behaviour_builder/build.gradle b/tgbotapi.behaviour_builder/build.gradle
index 7a3d80e9da..488052502a 100644
--- a/tgbotapi.behaviour_builder/build.gradle
+++ b/tgbotapi.behaviour_builder/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -43,7 +49,6 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
diff --git a/tgbotapi.core/build.gradle b/tgbotapi.core/build.gradle
index 01ba2f9b9d..20105eb576 100644
--- a/tgbotapi.core/build.gradle
+++ b/tgbotapi.core/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -94,7 +100,6 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
diff --git a/tgbotapi.extensions.api/build.gradle b/tgbotapi.extensions.api/build.gradle
index 2e59abfe91..ad5ab19c66 100644
--- a/tgbotapi.extensions.api/build.gradle
+++ b/tgbotapi.extensions.api/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -43,8 +49,7 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
diff --git a/tgbotapi.extensions.behaviour_builder.fsm/build.gradle b/tgbotapi.extensions.behaviour_builder.fsm/build.gradle
index 70bda66a94..aa2d82b664 100644
--- a/tgbotapi.extensions.behaviour_builder.fsm/build.gradle
+++ b/tgbotapi.extensions.behaviour_builder.fsm/build.gradle
@@ -43,8 +43,7 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
diff --git a/tgbotapi.extensions.behaviour_builder/build.gradle b/tgbotapi.extensions.behaviour_builder/build.gradle
index 4536301cf5..0167fa3ae8 100644
--- a/tgbotapi.extensions.behaviour_builder/build.gradle
+++ b/tgbotapi.extensions.behaviour_builder/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -43,8 +49,7 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
diff --git a/tgbotapi.extensions.utils/build.gradle b/tgbotapi.extensions.utils/build.gradle
index ad0a0d7910..a6a9ad771e 100644
--- a/tgbotapi.extensions.utils/build.gradle
+++ b/tgbotapi.extensions.utils/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -43,8 +49,7 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
 
diff --git a/tgbotapi.utils/build.gradle b/tgbotapi.utils/build.gradle
index eca97cef94..f5f75bdb2c 100644
--- a/tgbotapi.utils/build.gradle
+++ b/tgbotapi.utils/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -61,7 +67,6 @@ kotlin {
 }
 
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }
diff --git a/tgbotapi/build.gradle b/tgbotapi/build.gradle
index 5cd816bf7b..561e2722c6 100644
--- a/tgbotapi/build.gradle
+++ b/tgbotapi/build.gradle
@@ -26,7 +26,13 @@ repositories {
 }
 
 kotlin {
-    jvm()
+    jvm {
+        compilations.main {
+            kotlinOptions {
+                jvmTarget = "1.8"
+            }
+        }
+    }
     js(IR) {
         browser()
         nodejs()
@@ -46,10 +52,8 @@ kotlin {
     }
 }
 
-
 java {
-    toolchain {
-        languageVersion = JavaLanguageVersion.of(8)
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 }