diff --git a/pom.xml b/pom.xml
index 9a088f8..bd3b567 100644
--- a/pom.xml
+++ b/pom.xml
@@ -20,26 +20,26 @@
         <dependency>
             <groupId>io.reactivex.rxjava2</groupId>
             <artifactId>rxjava</artifactId>
-            <version>${rxjava.version}</version>
+            <version>2.2.3</version>
         </dependency>
 
         <!-- Logging -->
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
-            <version>${slf4j.version}</version>
+            <version>1.7.25</version>
         </dependency>
 
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>
-            <version>${slf4j.version}</version>
+            <version>1.7.25</version>
         </dependency>
 
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>4.13.1</version>
             <scope>test</scope>
         </dependency>