diff --git a/gradle.properties b/gradle.properties
index af70eca1b1..44118e81fe 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -73,6 +73,8 @@ pytorchNativeVersion=1.9.1
 shadowJarVersion=7.1.2
 openblasVersion=0.3.10-1.5.4
 arpackNgVersion=3.7.0-1.5.4
+#Please, specify absolute path to jdk8 rt.jar C:/Program Files/Java/jdk1.8.0_311/jre/lib/rt.jar
+jdk8Jar=""
 
 # configuration for build server
 org.gradle.daemon=false
diff --git a/utbot-junit-contest/build.gradle b/utbot-junit-contest/build.gradle
index dd40d660f7..0df57288bd 100644
--- a/utbot-junit-contest/build.gradle
+++ b/utbot-junit-contest/build.gradle
@@ -4,7 +4,7 @@ plugins {
 apply plugin: 'jacoco'
 
 configurations {
-    fetchInstrumentationJar
+    fetchInstrumentationJar.extendsFrom testImplementation
 }
 
 compileJava {
@@ -12,6 +12,10 @@ compileJava {
 }
 
 compileTestJava {
+    // Specify path to rt.jar of jdk8 in gradle.properties
+    options.bootstrapClasspath = files("${jdk8Jar}")
+    sourceCompatibility = '1.8'
+    targetCompatibility = '1.8'
     options.fork = true
     options.forkOptions.executable = 'javac'
     options.compilerArgs << "-XDignore.symbol.file"
@@ -74,6 +78,7 @@ dependencies {
 }
 
 processResources {
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
     from(configurations.fetchInstrumentationJar) {
         into "lib"
     }