diff --git a/build.gradle b/build.gradle
index b9c561885..89e24b5be 100644
--- a/build.gradle
+++ b/build.gradle
@@ -61,6 +61,7 @@ ext.versions = [
         mqlVersion : '3.4.+',
         nettyVersion : "4.1.34.Final",
         parquetVersion : "1.12.0",
+        rxJavaMathVersion : "0.20.6",
         rxJavaReactiveStreamsVersion : '1.+',
         scalaBinaryVersion : '2.12',
         snappyVersion : "1.1.+",
@@ -139,6 +140,7 @@ ext.libraries = [
         nettyHandler   : "io.netty:netty-handler:${versions.nettyVersion}",
         parquetHadoop  : "org.apache.parquet:parquet-hadoop:${versions.parquetVersion}",
         rxJava         : "io.reactivex:rxjava:1.3.8",
+        rxJavaMath     : "com.netflix.rxjava:rxjava-math:${versions.rxJavaMathVersion}",
         rxJavaReactiveStreams : "io.reactivex:rxjava-reactive-streams:${versions.rxJavaReactiveStreamsVersion}",
         rxNettyShaded  : "com.netflix:mantis-rxnetty:0.4.19.1",
         slf4jApi       : "org.slf4j:slf4j-api:${versions.slf4j}",
diff --git a/mantis-remote-observable/build.gradle b/mantis-remote-observable/build.gradle
index fd54815bd..a758641ad 100644
--- a/mantis-remote-observable/build.gradle
+++ b/mantis-remote-observable/build.gradle
@@ -14,10 +14,6 @@
  * limitations under the License.
  */
 
-ext {
-    nettyVersion = '4.1.17.Final'
-    rxJavaMathVersion = '0.20.6'
-}
 
 test {
     exclude 'io/reactivex/mantis/remote/observable/**'  // exclude remote observable tests that require ports
@@ -25,8 +21,8 @@ test {
 
 dependencies {
     implementation project(':mantis-common')
-    implementation "io.netty:netty-handler:$nettyVersion"
-    implementation("com.netflix.rxjava:rxjava-math:$rxJavaMathVersion") {
+    implementation libraries.nettyHandler
+    implementation(libraries.rxJavaMath) {
         exclude module: 'rxjava-core'
     }
     implementation libraries.slf4jApi