diff --git a/build.gradle b/build.gradle
index 3fe642542e..9d229b3aba 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,7 +4,7 @@ buildscript {
     file("$projectDir/constants.properties").withInputStream { constants.load(it) }
 
     // Our version: bump this on release.
-    ext.corda_release_version = "5.0-SNAPSHOT"
+    ext.corda_release_version = "4.0-RC05"
     ext.corda_platform_version = constants.getProperty("platformVersion")
     ext.gradle_plugins_version = constants.getProperty("gradlePluginsVersion")
 
diff --git a/constants.properties b/constants.properties
index 14f4bd71ed..97045c2585 100644
--- a/constants.properties
+++ b/constants.properties
@@ -4,7 +4,7 @@ kotlinVersion=1.2.71
 # When incrementing platformVersion make sure to update          #
 # net.corda.core.internal.CordaUtilsKt.PLATFORM_VERSION as well. #
 # ***************************************************************#
-platformVersion=5
+platformVersion=4
 guavaVersion=25.1-jre
 proguardVersion=6.0.3
 bouncycastleVersion=1.60
diff --git a/core/src/main/kotlin/net/corda/core/internal/CordaUtils.kt b/core/src/main/kotlin/net/corda/core/internal/CordaUtils.kt
index 9515c3c17d..0d6d6dfd6e 100644
--- a/core/src/main/kotlin/net/corda/core/internal/CordaUtils.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/CordaUtils.kt
@@ -25,7 +25,7 @@ import java.util.jar.JarInputStream
 
 // *Internal* Corda-specific utilities.
 
-const val PLATFORM_VERSION = 5
+const val PLATFORM_VERSION = 4
 
 fun ServicesForResolution.ensureMinimumPlatformVersion(requiredMinPlatformVersion: Int, feature: String) {
     checkMinimumPlatformVersion(networkParameters.minimumPlatformVersion, requiredMinPlatformVersion, feature)