diff --git a/build.json b/build.json
index 1cd03ffb38..9a8da37187 100644
--- a/build.json
+++ b/build.json
@@ -4,11 +4,11 @@
   "DotNetVersion": "3.0.100",
   "RequiredMonoVersion": "6.6.0",
   "DownloadURL": "https://roslynomnisharp.blob.core.windows.net/ext",
-  "MonoRuntimeMacOS": "mono.macOS-6.4.0.198.zip",
-  "MonoRuntimeLinux32": "mono.linux-x86-6.4.0.198.zip",
-  "MonoRuntimeLinux64": "mono.linux-x86_64-6.4.0.198.zip",
-  "MonoMSBuildRuntime": "Microsoft.Build.Runtime.Mono-6.4.0.198.zip",
-  "MonoMSBuildLib": "Microsoft.Build.Lib.Mono-6.4.0.198.zip",
+  "MonoRuntimeMacOS": "mono.macOS-6.6.0.161.zip",
+  "MonoRuntimeLinux32": "mono.linux-x86-6.6.0.161.zip",
+  "MonoRuntimeLinux64": "mono.linux-x86_64-6.6.0.161.zip",
+  "MonoMSBuildRuntime": "Microsoft.Build.Runtime.Mono-6.6.0.161.zip",
+  "MonoMSBuildLib": "Microsoft.Build.Lib.Mono-6.6.0.161.zip",
   "HostProjects": [
     "OmniSharp.Stdio.Driver",
     "OmniSharp.Http.Driver"