diff --git a/base/file.jl b/base/file.jl
index e557ffe9d1106..c3d246f61835b 100644
--- a/base/file.jl
+++ b/base/file.jl
@@ -554,76 +554,25 @@ end
 
 const temp_prefix = "jl_"
 
-if Sys.iswindows()
-
-function _win_tempname(temppath::AbstractString, uunique::UInt32)
-    tempp = cwstring(temppath)
-    temppfx = cwstring(temp_prefix)
-    tname = Vector{UInt16}(undef, 32767)
-    uunique = ccall(:GetTempFileNameW, stdcall, UInt32,
-                    (Ptr{UInt16}, Ptr{UInt16}, UInt32, Ptr{UInt16}),
-                    tempp, temppfx, uunique, tname)
-    windowserror("GetTempFileName", uunique == 0)
-    lentname = something(findfirst(iszero, tname))
-    @assert lentname > 0
-    resize!(tname, lentname - 1)
-    return transcode(String, tname)
-end
-
-function mktemp(parent::AbstractString=tempdir(); cleanup::Bool=true)
-    filename = _win_tempname(parent, UInt32(0))
-    cleanup && temp_cleanup_later(filename)
-    return (filename, Base.open(filename, "r+"))
-end
-
-# generate a random string from random bytes
-function _rand_string()
-    nchars = 10
-    A = Vector{UInt8}(undef, nchars)
-    windowserror("SystemFunction036 (RtlGenRandom)", 0 == ccall(
-        (:SystemFunction036, :Advapi32), stdcall, UInt8, (Ptr{Cvoid}, UInt32),
-            A, sizeof(A)))
-
-    slug = Base.StringVector(10)
+# Use `Libc.rand()` to generate random strings
+function _rand_filename(len = 10)
+    slug = Base.StringVector(len)
     chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-    for i = 1:nchars
-        slug[i] = chars[(A[i] % length(chars)) + 1]
+    for i = 1:len
+        slug[i] = chars[(Libc.rand() % length(chars)) + 1]
     end
-    return name = String(slug)
+    return String(slug)
 end
 
-function tempname(parent::AbstractString=tempdir(); cleanup::Bool=true)
-    isdir(parent) || throw(ArgumentError("$(repr(parent)) is not a directory"))
-    name = _rand_string()
-    filename = joinpath(parent, temp_prefix * name)
-    @assert !ispath(filename)
-    cleanup && temp_cleanup_later(filename)
-    return filename
-end
-
-else # !windows
-
-# Based of musl __randname
-function _rand_string()
-    r = Base.rand(UInt) # FIXME: https://git.musl-libc.org/cgit/musl/tree/src/temp/__randname.c
-    buf = Vector{Char}(undef, 6)
-    for i in 1:6
-        buf[i] = 'A'+(r&15)+(r&16)*2;
-        r >>= 5
-    end
-    String(buf)
-end
 
 # Obtain a temporary filename.
-function tempname(parent::AbstractString=tempdir(); cleanup::Bool=true)
+function tempname(parent::AbstractString=tempdir(); max_tries::Int = 100, cleanup::Bool=true)
     isdir(parent) || throw(ArgumentError("$(repr(parent)) is not a directory"))
 
     prefix = joinpath(parent, temp_prefix)
-    MAX_TRIES = 100
-
     filename = nothing
-    for i in 1:MAX_TRIES
-        filename = string(prefix, _rand_string())
+    for i in 1:max_tries
+        filename = string(prefix, _rand_filename())
         if ispath(filename)
             filename = nothing
         else
@@ -632,13 +581,36 @@ function tempname(parent::AbstractString=tempdir(); cleanup::Bool=true)
     end
 
     if filename === nothing
-        error("tempname: MAX_TRIES exhausted")
+        error("tempname: max_tries exhausted")
     end
 
     cleanup && temp_cleanup_later(filename)
     return filename
 end
 
+if Sys.iswindows()
+function _win_tempname(temppath::AbstractString, uunique::UInt32)
+    tempp = cwstring(temppath)
+    temppfx = cwstring(temp_prefix)
+    tname = Vector{UInt16}(undef, 32767)
+    uunique = ccall(:GetTempFileNameW, stdcall, UInt32,
+                    (Ptr{UInt16}, Ptr{UInt16}, UInt32, Ptr{UInt16}),
+                    tempp, temppfx, uunique, tname)
+    windowserror("GetTempFileName", uunique == 0)
+    lentname = something(findfirst(iszero, tname))
+    @assert lentname > 0
+    resize!(tname, lentname - 1)
+    return transcode(String, tname)
+end
+
+function mktemp(parent::AbstractString=tempdir(); cleanup::Bool=true)
+    filename = _win_tempname(parent, UInt32(0))
+    cleanup && temp_cleanup_later(filename)
+    return (filename, Base.open(filename, "r+"))
+end
+
+else # !windows
+
 # Create and return the name of a temporary file along with an IOStream
 function mktemp(parent::AbstractString=tempdir(); cleanup::Bool=true)
     b = joinpath(parent, temp_prefix * "XXXXXX")
@@ -648,7 +620,6 @@ function mktemp(parent::AbstractString=tempdir(); cleanup::Bool=true)
     return (b, fdio(p, true))
 end
 
-
 end # os-test
 
 
diff --git a/test/file.jl b/test/file.jl
index b4983ac5e61c5..a7c0b6dca125d 100644
--- a/test/file.jl
+++ b/test/file.jl
@@ -117,7 +117,7 @@ end
     # 38873: check that `TMPDIR` being set does not
     # override the parent argument to `tempname`.
     mktempdir() do d
-        whithenv("TMPDIR"=>tmpdir()) do
+        withenv("TMPDIR"=>tempdir()) do
             t = tempname(d)
             @test dirname(t) == d
         end