diff --git a/lib/kotlin/cross-test-client/build.gradle.kts b/lib/kotlin/cross-test-client/build.gradle.kts
index 579d01e..b370a40 100644
--- a/lib/kotlin/cross-test-client/build.gradle.kts
+++ b/lib/kotlin/cross-test-client/build.gradle.kts
@@ -70,7 +70,7 @@
 
     task<Exec>("compileThrift") {
         val thriftBin = if (hasProperty("thrift.compiler")) {
-            file(property("thrift.compiler"))
+            file(property("thrift.compiler")!!)
         } else {
             project.rootDir.resolve("../../compiler/cpp/thrift")
         }