diff --git a/src/NIfTI.jl b/src/NIfTI.jl
index d63a0c3..d7c4510 100644
--- a/src/NIfTI.jl
+++ b/src/NIfTI.jl
@@ -81,21 +81,21 @@ NIVolume{T<:Number,N}(header::NIfTI1Header, raw::Array{T,N}) =
 
 const SIZEOF_HDR = int32(348)
 
-const NIfTI_DT_BITSTYPES = (Int16=>Type)[
-    int16(2) => Uint8,
-    int16(4) => Int16,
-    int16(8) => Int32,
-    int16(16) => Float32,
-    int16(32) => Complex64,
-    int16(64) => Float64,
-    int16(256) => Int8,
-    int16(512) => Uint16, 
-    int16(768) => Uint32,
-    int16(1024) => Int64,
-    int16(1280) => Uint64,
-    int16(1792) => Complex128
-]
-const NIfTI_DT_BITSTYPES_REVERSE = (Type=>Int16)[]
+const NIfTI_DT_BITSTYPES = Dict{Int16,Type}([
+    (int16(2), Uint8),
+    (int16(4), Int16),
+    (int16(8), Int32),
+    (int16(16), Float32),
+    (int16(32), Complex64),
+    (int16(64), Float64),
+    (int16(256), Int8),
+    (int16(512), Uint16),
+    (int16(768), Uint32),
+    (int16(1024), Int64),
+    (int16(1280), Uint64),
+    (int16(1792), Complex128)
+])
+const NIfTI_DT_BITSTYPES_REVERSE = Dict{Type,Int16}()
 for (k, v) in NIfTI_DT_BITSTYPES
     NIfTI_DT_BITSTYPES_REVERSE[v] = k
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index 0a54ff3..1427608 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -36,8 +36,8 @@ for (fname, mmap) in ((NII, false), (NII, true), (HDR, false), (HDR, true),
 	@test vox(file, 69, 56, 13, :)[:] == [502, 521]
 end
 
-@test_throws niread(GZIPPED_NII; mmap=true)
-@test_throws niread(GZIPPED_HDR; mmap=true)
+@test_throws ErrorException niread(GZIPPED_NII; mmap=true)
+@test_throws ErrorException niread(GZIPPED_HDR; mmap=true)
 
 # Test writing
 const TEMP_FILE = "$(tempname()).nii"