diff --git a/.travis.yml b/.travis.yml
index 0c7e97f..8d20ddd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,12 +11,18 @@ matrix:
     - os: linux
       julia: 1.2
       env: TESTCMD="xvfb-run julia"
+    - os: linux
+      julia: 1.3
+      env: TESTCMD="xvfb-run julia"
     - os: linux
       julia: nightly
       env: TESTCMD="xvfb-run julia"
     - os: osx
       julia: 1.0
       env: TESTCMD="julia"
+    - os: osx
+      julia: 1.2
+      env: TESTCMD="julia"
     - os: osx
       julia: nightly
       env: TESTCMD="julia"
@@ -42,8 +48,6 @@ before_install:
 
 script:
   - julia --color=yes -e "using Pkg; if VERSION >= v\"1.1.0-rc1\"; Pkg.build(verbose=true); else Pkg.build(); end"
-  # work-around for https://github.com/JuliaWeb/MbedTLS.jl/issues/193
-  - julia --color=yes -e "using Pkg; if VERSION >= v\"1.2.0\"; Pkg.update(\"MbedTLS\"); end"
   - $TESTCMD --check-bounds=yes --color=yes -e 'using Pkg; Pkg.test("MeshCat", coverage=true)'
   - julia --color=yes -e 'using MeshCat; MeshCat.develop_meshcat_assets(true)'
   - julia --color=yes -e 'import Pkg; Pkg.build("MeshCat")'
diff --git a/Project.toml b/Project.toml
index d5218e5..6a3bcac 100644
--- a/Project.toml
+++ b/Project.toml
@@ -29,6 +29,7 @@ AssetRegistry = "0.1"
 Cassette = "0.2.5"
 GeometryTypes = "0.6, 0.7"
 JSExpr = "0.3, 0.5"
+MsgPack = "1"
 Mux = "0.7"
 WebIO = "0.8.11"
 julia = "0.7, 1"
diff --git a/src/MeshCat.jl b/src/MeshCat.jl
index 2b74511..5686ca6 100644
--- a/src/MeshCat.jl
+++ b/src/MeshCat.jl
@@ -21,7 +21,7 @@ using UUIDs: UUID, uuid1
 using LinearAlgebra: UniformScaling, Diagonal, norm
 using Sockets: listen, @ip_str, IPAddr, IPv4, IPv6
 using Base64: base64encode
-using MsgPack: MsgPack, pack, Ext
+using MsgPack: MsgPack, pack
 
 import Base: delete!
 
diff --git a/src/msgpack.jl b/src/msgpack.jl
index 1215e0e..51bc1af 100644
--- a/src/msgpack.jl
+++ b/src/msgpack.jl
@@ -4,7 +4,7 @@ extcode(::Type{Int32}) = 0x15
 extcode(::Type{UInt32}) = 0x16
 extcode(::Type{Float32}) = 0x17
 
-MsgPack.pack(io::IO, v::PackedVector) = pack(io, Ext(extcode(v),
+MsgPack.pack(io::IO, v::PackedVector) = pack(io, MsgPack.Extension(extcode(v),
     convert(Vector{UInt8},
         reshape(reinterpret(UInt8, v.data),
             (sizeof(v.data),)))))