diff --git a/base/utf8.jl b/base/utf8.jl
index 7b30ac0f37e07..7986dff9285ea 100644
--- a/base/utf8.jl
+++ b/base/utf8.jl
@@ -220,12 +220,8 @@ convert(::Type{UTF8String}, s::ASCIIString) = UTF8String(s.data)
 "
 Converts a UTF-8 encoded vector of `UInt8` to a `UTF8String`
 
-### Input Arguments:
-*   `::Type{UTF8String}`
-*   `dat::Vector{UInt8}`
-
 ### Returns:
-*   `::UTF8String`
+*   `UTF8String`
 
 ### Throws:
 *   `UnicodeError`
@@ -234,7 +230,7 @@ function convert(::Type{UTF8String}, dat::Vector{UInt8})
     # handle zero length string quickly
     isempty(dat) && return empty_utf8
     # get number of bytes to allocate
-    len, flags, num4byte, num3byte, num2byte = check_string(dat)
+    len, flags, num4byte, num3byte, num2byte = unsafe_checkstring(dat)
     if (flags & (UTF_LONG | UTF_SURROGATE)) == 0
         len = sizeof(dat)
         @inbounds return UTF8String(copy!(Vector{UInt8}(len), 1, dat, 1, len))