diff --git a/src/C_interface.jl b/src/C_interface.jl
index 4509f98..4880bcd 100644
--- a/src/C_interface.jl
+++ b/src/C_interface.jl
@@ -8,19 +8,19 @@ function readstat_get_modified_time(metadata::Ptr{Nothing})
 end
 
 function readstat_get_file_format_version(metadata::Ptr{Nothing})
-    return ccall((:readstat_get_file_format_version, libreadstat), UInt, (Ptr{Nothing},), metadata)
+    return ccall((:readstat_get_file_format_version, libreadstat), Cint, (Ptr{Nothing},), metadata)
 end
 
 function readstat_get_row_count(metadata::Ptr{Nothing})
-    return ccall((:readstat_get_row_count, libreadstat), UInt, (Ptr{Nothing},), metadata)
+    return ccall((:readstat_get_row_count, libreadstat), Cint, (Ptr{Nothing},), metadata)
 end
 
 function readstat_get_var_count(metadata::Ptr{Nothing})
-    return ccall((:readstat_get_var_count, libreadstat), UInt, (Ptr{Nothing},), metadata)
+    return ccall((:readstat_get_var_count, libreadstat), Cint, (Ptr{Nothing},), metadata)
 end
 
 function readstat_value_is_missing(value::ReadStatValue, variable::Ptr{Nothing})
-    return ccall((:readstat_value_is_missing, libreadstat), Bool, (ReadStatValue,Ptr{Nothing}), value, variable)
+    return Bool(ccall((:readstat_value_is_missing, libreadstat), Cint, (ReadStatValue,Ptr{Nothing}), value, variable))
 end
 
 function readstat_variable_get_index(variable::Ptr{Nothing})
@@ -56,19 +56,23 @@ function readstat_value_type(val::Value)
 end
 
 function readstat_parse(filename::String, type::Val{:dta}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
-    return ccall((:readstat_parse_dta, libreadstat), Int, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
+    return ccall((:readstat_parse_dta, libreadstat), Cint, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
 end
 
 function readstat_parse(filename::String, type::Val{:sav}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
-    return ccall((:readstat_parse_sav, libreadstat), Int, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
+    return ccall((:readstat_parse_sav, libreadstat), Cint, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
 end
 
 function readstat_parse(filename::String, type::Val{:por}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
-    return ccall((:readstat_parse_por, libreadstat), Int, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
+    return ccall((:readstat_parse_por, libreadstat), Cint, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
 end
 
 function readstat_parse(filename::String, type::Val{:sas7bdat}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
-    return ccall((:readstat_parse_sas7bdat, libreadstat), Int, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
+    return ccall((:readstat_parse_sas7bdat, libreadstat), Cint, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
+end
+
+function readstat_parse(filename::String, type::Val{:xport}, parser::Ptr{Nothing}, ds::ReadStatDataFrame)
+    return ccall((:readstat_parse_xport, libreadstat), Cint, (Ptr{Nothing}, Cstring, Any), parser, string(filename), ds)
 end
 
 function readstat_variable_get_missing_ranges_count(variable::Ptr{Nothing})
diff --git a/src/ReadStat.jl b/src/ReadStat.jl
index eb4565f..6979f3a 100644
--- a/src/ReadStat.jl
+++ b/src/ReadStat.jl
@@ -12,7 +12,7 @@ using DataValues: DataValueVector
 import DataValues
 using Dates
 
-export ReadStatDataFrame, read_dta, read_sav, read_por, read_sas7bdat
+export ReadStatDataFrame, read_dta, read_sav, read_por, read_sas7bdat, read_xport
 
 ##############################################################################
 ##
@@ -72,7 +72,7 @@ mutable struct ReadStatDataFrame
     types_as_int::Vector{Cint}
     hasmissings::Vector{Bool}
 
-    ReadStatDataFrame() = 
+    ReadStatDataFrame() =
         new(Any[], Symbol[], DataType[], String[], String[], Csize_t[], Cint[], Cint[],
         String[], Dict{String, Dict{Any,String}}(), 0, 0, "", Dates.unix2datetime(0), 0, Cint[], Bool[])
 end
@@ -114,9 +114,7 @@ function get_format(var::Ptr{Nothing})
     ptr == C_NULL ? "" : unsafe_string(ptr)
 end
 
-function get_type(variable::Ptr{Nothing})
-    data_type = readstat_variable_get_type(variable)
-
+function get_type(data_type::Cint)
     if data_type == READSTAT_TYPE_STRING
         return String
     elseif data_type == READSTAT_TYPE_CHAR
@@ -132,6 +130,7 @@ function get_type(variable::Ptr{Nothing})
     end
     return Nothing
 end
+get_type(variable::Ptr{Nothing}) = get_type(readstat_variable_get_type(variable))
 
 get_storagewidth(variable::Ptr{Nothing}) = readstat_variable_get_storage_width(variable)
 
@@ -139,11 +138,10 @@ get_measure(variable::Ptr{Nothing}) = readstat_variable_get_measure(variable)
 
 get_alignment(variable::Ptr{Nothing}) = readstat_variable_get_measure(variable)
 
-function handle_variable!(var_index::Cint, variable::Ptr{Nothing}, 
+function handle_variable!(var_index::Cint, variable::Ptr{Nothing},
                          val_label::Cstring,  ds_ptr::Ptr{ReadStatDataFrame})
     col = var_index + 1
     ds = unsafe_pointer_to_objref(ds_ptr)::ReadStatDataFrame
-
     missing_count = readstat_variable_get_missing_ranges_count(variable)
 
     push!(ds.val_label_keys, (val_label == C_NULL ? "" : unsafe_string(val_label)))
@@ -154,11 +152,16 @@ function handle_variable!(var_index::Cint, variable::Ptr{Nothing},
     push!(ds.types, jtype)
     push!(ds.types_as_int, readstat_variable_get_type(variable))
     push!(ds.hasmissings, missing_count > 0)
-    push!(ds.data, DataValueVector{jtype}(Vector{jtype}(undef, ds.rows), fill(false, ds.rows)))
+    # SAS XPORT sets ds.rows == -1
+    if ds.rows >= 0
+        push!(ds.data, DataValueVector{jtype}(Vector{jtype}(undef, ds.rows), fill(false, ds.rows)))
+    else
+        push!(ds.data, DataValueVector{jtype}(Vector{jtype}(undef, 0), fill(false, 0)))
+    end
     push!(ds.storagewidths, get_storagewidth(variable))
     push!(ds.measures, get_measure(variable))
     push!(ds.alignments, get_alignment(variable))
-    
+
     return Cint(0)
 end
 
@@ -191,62 +194,17 @@ function handle_value!(obs_index::Cint, variable::Ptr{Nothing},
         readstat_value_is_missing(value, C_NULL)
     end
 
-    if type_as_int==READSTAT_TYPE_DOUBLE
-        col_float64 = data[var_index]::DataValueVector{Float64}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_float64, true, obs_index + 1)
-        else
-            readfield!(col_float64, obs_index + 1, value)
-        end
-    elseif type_as_int==READSTAT_TYPE_INT32
-        col_int32 = data[var_index]::DataValueVector{Int32}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_int32, true, obs_index + 1)
-        else
-            readfield!(col_int32, obs_index + 1, value)
-        end
-    elseif type_as_int==READSTAT_TYPE_STRING
-        col_string = data[var_index]::DataValueVector{String}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_string, true, obs_index + 1)
-        else
-            readfield!(col_string, obs_index + 1, value)
-        end
-    elseif type_as_int==READSTAT_TYPE_CHAR
-        col_int8 = data[var_index]::DataValueVector{Int8}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_int8, true, obs_index + 1)
-        else
-            readfield!(col_int8, obs_index + 1, value)
-        end
-    elseif type_as_int==READSTAT_TYPE_INT16
-        col_int16 = data[var_index]::DataValueVector{Int16}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_int16, true, obs_index + 1)
-        else
-            readfield!(col_int16, obs_index + 1, value)
-        end
-    elseif type_as_int==READSTAT_TYPE_FLOAT
-        col_float32 = data[var_index]::DataValueVector{Float32}
-
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_float32, true, obs_index + 1)
-        else
-            readfield!(col_float32, obs_index + 1, value)
-        end
-    else        
-        col_untyped = data[var_index]
+    col = data[var_index]
+    @assert eltype(eltype(col)) == get_type(type_as_int)
 
-        if ismissing
-            DataValues.unsafe_setindex_isna!(col_untyped, true, obs_index + 1)
+    if ismissing
+        if obs_index < length(col)
+            DataValues.unsafe_setindex_isna!(col, true, obs_index + 1)
         else
-            readfield!(col_untyped, obs_index + 1, value)
+            push!(col, DataValues.NA)
         end
+    else
+        readfield!(col, obs_index + 1, value)
     end
 
     return Cint(0)
@@ -254,29 +212,35 @@ end
 
 function readfield!(dest::DataValueVector{String}, row, val::ReadStatValue)
     ptr = ccall((:readstat_string_value, libreadstat), Cstring, (ReadStatValue,), val)
-    if ptr ≠ C_NULL
-        @inbounds DataValues.unsafe_setindex_value!(dest, unsafe_string(ptr), row)
-    end
-end
-
-function readfield!(dest::DataValueVector{Int8}, row, val::ReadStatValue)
-    @inbounds DataValues.unsafe_setindex_value!(dest, ccall((:readstat_int8_value, libreadstat), Int8, (ReadStatValue,), val), row)
-end
-
-function readfield!(dest::DataValueVector{Int16}, row, val::ReadStatValue)
-    @inbounds DataValues.unsafe_setindex_value!(dest, ccall((:readstat_int16_value, libreadstat), Int16, (ReadStatValue,), val), row)
-end
 
-function readfield!(dest::DataValueVector{Int32}, row, val::ReadStatValue)
-    @inbounds DataValues.unsafe_setindex_value!(dest, ccall((:readstat_int32_value, libreadstat), Int32, (ReadStatValue,), val), row)
-end
-
-function readfield!(dest::DataValueVector{Float64}, row, val::ReadStatValue)
-    @inbounds DataValues.unsafe_setindex_value!(dest, ccall((:readstat_double_value, libreadstat), Float64, (ReadStatValue,), val), row)
+    if row <= length(dest)
+        if ptr ≠ C_NULL
+            @inbounds DataValues.unsafe_setindex_value!(dest, unsafe_string(ptr), row)
+        end
+    elseif row == length(dest) + 1
+        _val = ptr ≠ C_NULL ? unsafe_string(ptr) : ""
+        DataValues.push!(dest, _val)
+    else
+        throw(ArgumentError("illegal row index: $row"))
+    end
 end
 
-function readfield!(dest::DataValueVector{Float32}, row, val::ReadStatValue)
-    @inbounds DataValues.unsafe_setindex_value!(dest, ccall((:readstat_float_value, libreadstat), Float32, (ReadStatValue,), val), row)
+for (j_type, rs_name) in (
+    (Int8,    :readstat_int8_value),
+    (Int16,   :readstat_int16_value),
+    (Int32,   :readstat_int32_value),
+    (Float32, :readstat_float_value),
+    (Float64, :readstat_double_value))
+    @eval function readfield!(dest::DataValueVector{$j_type}, row, val::ReadStatValue)
+        _val = ccall(($(QuoteNode(rs_name)), libreadstat), $j_type, (ReadStatValue,), val)
+        if row <= length(dest)
+            @inbounds DataValues.unsafe_setindex_value!(dest, _val, row)
+        elseif row == length(dest) + 1
+            DataValues.push!(dest, _val)
+        else
+            throw(ArgumentError("illegal row index: $row"))
+        end
+    end
 end
 
 function handle_value_label!(val_labels::Cstring, value::Value, label::Cstring, ds_ptr::Ptr{ReadStatDataFrame})
@@ -284,7 +248,7 @@ function handle_value_label!(val_labels::Cstring, value::Value, label::Cstring,
     ds = unsafe_pointer_to_objref(ds_ptr)
     dict = get!(ds.val_label_dict, unsafe_string(val_labels), Dict{Any,String}())
     dict[as_native(value)] = unsafe_string(label)
-    
+
     return Cint(0)
 end
 
@@ -311,7 +275,7 @@ function Parser()
     ccall((:readstat_set_value_handler, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}), parser, val_fxn)
     ccall((:readstat_set_value_label_handler, libreadstat), Int, (Ptr{Nothing}, Ptr{Nothing}), parser, label_fxn)
     return parser
-end  
+end
 
 function parse_data_file!(ds::ReadStatDataFrame, parser::Ptr{Nothing}, filename::AbstractString, filetype::Val)
     retval = readstat_parse(filename, filetype, parser, ds)
@@ -323,5 +287,6 @@ read_dta(filename::AbstractString) = read_data_file(filename, Val(:dta))
 read_sav(filename::AbstractString) = read_data_file(filename, Val(:sav))
 read_por(filename::AbstractString) = read_data_file(filename, Val(:por))
 read_sas7bdat(filename::AbstractString) = read_data_file(filename, Val(:sas7bdat))
+read_xport(filename::AbstractString) = read_data_file(filename, Val(:xport))
 
 end #module ReadStat
diff --git a/test/runtests.jl b/test/runtests.jl
index 97e6b81..dbc10b0 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2,54 +2,22 @@ using ReadStat
 using DataValues
 using Test
 
-@testset "ReadStat" begin
-
-@testset "DTA files" begin
-
-dtafile = joinpath(dirname(@__FILE__), "types.dta")
-rsdf = read_dta(dtafile)
-data = rsdf.data
-
-@test length(data) == 6
-@test rsdf.headers == [:vfloat, :vdouble, :vlong, :vint, :vbyte, :vstring]
-@test data[1] == DataValueArray{Float32}([3.14, 7., NA])
-@test data[2] == DataValueArray{Float64}([3.14, 7., NA])
-@test data[3] == DataValueArray{Int32}([2, 7, NA])
-@test data[4] == DataValueArray{Int16}([2, 7, NA])
-@test data[5] == DataValueArray{Int8}([2, 7., NA])
-@test data[6] == DataValueArray{String}(["2", "7", ""])
-end
-
-@testset "SAV files" begin
-
-dtafile = joinpath(dirname(@__FILE__), "types.sav")
-rsdf = read_sav(dtafile)
-data = rsdf.data
-
-@test length(data) == 6
-@test rsdf.headers == [:vfloat, :vdouble, :vlong, :vint, :vbyte, :vstring]
-@test data[1] == DataValueArray{Float32}([3.14, 7., NA])
-@test data[2] == DataValueArray{Float64}([3.14, 7., NA])
-@test data[3] == DataValueArray{Int32}([2, 7, NA])
-@test data[4] == DataValueArray{Int16}([2, 7, NA])
-@test data[5] == DataValueArray{Int8}([2, 7., NA])
-@test data[6] == DataValueArray{String}(["2", "7", ""])
-end
-
-@testset "SAS7BDAT files" begin
-
-dtafile = joinpath(dirname(@__FILE__), "types.sas7bdat")
-rsdf = read_sas7bdat(dtafile)
-data = rsdf.data
-
-@test length(data) == 6
-@test rsdf.headers == [:vfloat, :vdouble, :vlong, :vint, :vbyte, :vstring]
-@test data[1] == DataValueArray{Float32}([3.14, 7., NA])
-@test data[2] == DataValueArray{Float64}([3.14, 7., NA])
-@test data[3] == DataValueArray{Int32}([2, 7, NA])
-@test data[4] == DataValueArray{Int16}([2, 7, NA])
-@test data[5] == DataValueArray{Int8}([2, 7., NA])
-@test data[6] == DataValueArray{String}(["2", "7", ""])
-end
-
+@testset "ReadStat: $ext files" for (reader, ext) in
+    ((read_dta, "dta"),
+     (read_sav, "sav"),
+     (read_sas7bdat, "sas7bdat"),
+     (read_xport, "xpt"))
+
+    dtafile = joinpath(dirname(@__FILE__), "types.$ext")
+    rsdf = reader(dtafile)
+    data = rsdf.data
+
+    @test length(data) == 6
+    @test rsdf.headers == [:vfloat, :vdouble, :vlong, :vint, :vbyte, :vstring]
+    @test data[1] == DataValueArray{Float32}([3.14, 7., NA])
+    @test data[2] == DataValueArray{Float64}([3.14, 7., NA])
+    @test data[3] == DataValueArray{Int32}([2, 7, NA])
+    @test data[4] == DataValueArray{Int16}([2, 7, NA])
+    @test data[5] == DataValueArray{Int8}([2, 7., NA])
+    @test data[6] == DataValueArray{String}(["2", "7", ""])
 end
diff --git a/test/types.xpt b/test/types.xpt
new file mode 100644
index 0000000..be4cb7c
Binary files /dev/null and b/test/types.xpt differ