diff --git a/.travis.yml b/.travis.yml
index 8c9d313..f6bbfe3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,6 @@ os:
 notifications:
   email: false
 julia:
-  - 0.3
   - 0.4
   - 0.5
   - nightly
diff --git a/REQUIRE b/REQUIRE
index 04dc960..c7eded8 100644
--- a/REQUIRE
+++ b/REQUIRE
@@ -1,2 +1,2 @@
-julia 0.3
-Compat 0.7.20
+julia 0.4
+Compat 0.17.0
diff --git a/appveyor.yml b/appveyor.yml
index ae0c159..063cc6e 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,7 +1,5 @@
 environment:
   matrix:
-  - JULIAVERSION: "julialang/bin/winnt/x86/0.3/julia-0.3-latest-win32.exe"
-  - JULIAVERSION: "julialang/bin/winnt/x64/0.3/julia-0.3-latest-win64.exe"
   - JULIAVERSION: "julialang/bin/winnt/x86/0.4/julia-0.4-latest-win32.exe"
   - JULIAVERSION: "julialang/bin/winnt/x64/0.4/julia-0.4-latest-win64.exe"
   - JULIAVERSION: "julialang/bin/winnt/x86/0.5/julia-0.5-latest-win32.exe"
@@ -35,4 +33,4 @@ build_script:
       Pkg.clone(pwd(), \"Codecs\"); Pkg.build(\"Codecs\")"
 
 test_script:
-  - C:\projects\julia\bin\julia --check-bounds=yes -e "Pkg.test(\"Codecs\")"
\ No newline at end of file
+  - C:\projects\julia\bin\julia --check-bounds=yes -e "Pkg.test(\"Codecs\")"
diff --git a/src/Codecs.jl b/src/Codecs.jl
index 42a4afb..d273704 100644
--- a/src/Codecs.jl
+++ b/src/Codecs.jl
@@ -7,7 +7,7 @@ using Compat
 
 export encode, decode, Base64, Zlib, BCD
 
-abstract Codec
+@compat abstract type Codec end
 
 
 function encode{T <: Codec}(codec::Type{T}, s::AbstractString)
@@ -22,7 +22,7 @@ end
 
 # RFC3548/RFC4648 base64 codec
 
-abstract Base64 <: Codec
+@compat abstract type Base64 <: Codec end
 
 const b64enc_tbl = UInt8[
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
@@ -53,11 +53,11 @@ end
 function encode(::Type{Base64}, input::Vector{UInt8})
     n = length(input)
     if n == 0
-        return Array(UInt8, 0)
+        return Vector{UInt8}(0)
     end
 
     m = @compat Int(4 * ceil(n / 3))
-    output = Array(UInt8, m)
+    output = Vector{UInt8}(m)
 
     k = 1
     for ii = 1:3:length(input)-2
@@ -89,7 +89,7 @@ end
 function decode(::Type{Base64}, input::Vector{UInt8})
     n = length(input)
     if n == 0
-        return Array(UInt8, 0)
+        return Vector{UInt8}(0)
     end
 
     if n % 4 != 0
@@ -103,7 +103,7 @@ function decode(::Type{Base64}, input::Vector{UInt8})
     if input[end - 1] == base64_pad
         m -= 1
     end
-    output = Array(UInt8, m)
+    output = Vector{UInt8}(m)
 
     k = 1
     @inbounds for ii = 1:4:length(input)-4
@@ -156,7 +156,7 @@ end
 
 # Zlib/Gzip
 
-abstract Zlib <: Codec
+@compat abstract type Zlib <: Codec end
 
 const Z_NO_FLUSH      = 0
 const Z_PARTIAL_FLUSH = 1
@@ -247,8 +247,8 @@ function encode(::Type{Zlib}, input::Vector{UInt8}, level::Integer)
     strm.next_in = input
     strm.avail_in = length(input)
     strm.total_in = length(input)
-    output = Array(UInt8, 0)
-    outbuf = Array(UInt8, 1024)
+    output = Vector{UInt8}(0)
+    outbuf = Vector{UInt8}(1024)
     ret = Z_OK
 
     while ret != Z_STREAM_END
@@ -297,8 +297,8 @@ function decode(::Type{Zlib}, input::Vector{UInt8})
     strm.next_in = input
     strm.avail_in = length(input)
     strm.total_in = length(input)
-    output = Array(UInt8, 0)
-    outbuf = Array(UInt8, 1024)
+    output = Vector{UInt8}(0)
+    outbuf = Vector{UInt8}(1024)
     ret = Z_OK
 
     while ret != Z_STREAM_END
@@ -330,7 +330,7 @@ end
 # Packed binary-coded decimal (BCD) integers
 # Two decimal digits per byte, each represented with 4 bits
 
-abstract BCD <: Codec
+@compat abstract type BCD <: Codec end
 
 function encode(::Type{BCD}, i::Integer, bigendian::Bool = false)
     if i < 0
@@ -340,7 +340,7 @@ function encode(::Type{BCD}, i::Integer, bigendian::Bool = false)
     ndig += isodd(ndig)
     v = digits(i, 10, ndig)
     nbytes = @compat trunc(Integer, ndig/2)
-    out = Array(UInt8, nbytes)
+    out = Vector{UInt8}(nbytes)
     dj = 1-2*bigendian
     for i = 1:nbytes
         j = bigendian*length(v) + dj*2*(i-1) + 1-bigendian