diff --git a/README.md b/README.md
index 5e498609c..0450f2b85 100644
--- a/README.md
+++ b/README.md
@@ -263,6 +263,11 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `codeunits(s)` returns an array-like view of the `UInt8` code units of
   a string and `ncodeunits(s)` returns the number of code units ([#25241]).
+  `codeunit(s)` returns the type of the code units of `s` ([#24999]).
+
+* `thisind(s, i)` returns the character index for codeunit `i` ([#24414]).
+
+* Three-argument methods `prevind(s,i,n)`, `nextind(s,i,n)` ([#23805]), and `length(s,i,j)` ([#24999]); the latter two replace `chr2ind` and `ind2chr` in Julia 0.7, respectively.
 
 * `printstyled` prints to a given stream optionally in color and/or bolded ([#25522]).
 
@@ -562,12 +567,14 @@ includes this fix. Find the minimum version from there.
 [#23642]: https://github.com/JuliaLang/julia/issues/23642
 [#23666]: https://github.com/JuliaLang/julia/issues/23666
 [#23757]: https://github.com/JuliaLang/julia/issues/23757
+[#23805]: https://github.com/JuliaLang/julia/issues/23805
 [#23931]: https://github.com/JuliaLang/julia/issues/23931
 [#24047]: https://github.com/JuliaLang/julia/issues/24047
 [#24182]: https://github.com/JuliaLang/julia/issues/24182
 [#24282]: https://github.com/JuliaLang/julia/issues/24282
 [#24361]: https://github.com/JuliaLang/julia/issues/24361
 [#24372]: https://github.com/JuliaLang/julia/issues/24372
+[#24414]: https://github.com/JuliaLang/julia/issues/24414
 [#24443]: https://github.com/JuliaLang/julia/issues/24443
 [#24459]: https://github.com/JuliaLang/julia/issues/24459
 [#24490]: https://github.com/JuliaLang/julia/issues/24490
@@ -582,6 +589,7 @@ includes this fix. Find the minimum version from there.
 [#24808]: https://github.com/JuliaLang/julia/issues/24808
 [#24831]: https://github.com/JuliaLang/julia/issues/24831
 [#24874]: https://github.com/JuliaLang/julia/issues/24874
+[#24999]: https://github.com/JuliaLang/julia/issues/24999
 [#25012]: https://github.com/JuliaLang/julia/issues/25012
 [#25021]: https://github.com/JuliaLang/julia/issues/25021
 [#25056]: https://github.com/JuliaLang/julia/issues/25056
diff --git a/src/Compat.jl b/src/Compat.jl
index 915ff6ef4..8d018b591 100644
--- a/src/Compat.jl
+++ b/src/Compat.jl
@@ -1925,6 +1925,60 @@ end
     export @cfunction
 end
 
+if VERSION < v"0.7.0-DEV.2920" # julia#24999
+    Base.length(s::AbstractString, i::Integer, j::Integer) = length(s, Int(i), Int(j))
+    function Base.length(s::AbstractString, i::Int, j::Int)
+        @boundscheck begin
+            0 < i ≤ ncodeunits(s)+1 || throw(BoundsError(s, i))
+            0 ≤ j < ncodeunits(s)+1 || throw(BoundsError(s, j))
+        end
+        n = 0
+        for k = i:j
+            @inbounds n += isvalid(s, k)
+        end
+        return n
+    end
+    Base.codeunit(s::String) = UInt8
+    Base.codeunit(s::SubString) = codeunit(s.string)
+end
+if !isdefined(Base, :thisind) # #24414
+    thisind(s::AbstractString, i::Integer) = thisind(s, Int(i))
+    function thisind(s::AbstractString, i::Int)
+        z = ncodeunits(s) + 1
+        i == z && return i
+        @boundscheck 0 ≤ i ≤ z || throw(BoundsError(s, i))
+        @inbounds while 1 < i && !isvalid(s, i)
+            i -= 1
+        end
+        return i
+    end
+    export thisind
+end
+if VERSION < v"0.7.0-DEV.2019" # julia#23805
+    Base.prevind(s::AbstractString, i::Integer, n::Integer) = prevind(s, Int(i), Int(n))
+    Base.nextind(s::AbstractString, i::Integer, n::Integer) = nextind(s, Int(i), Int(n))
+    function Base.nextind(s::AbstractString, i::Int, n::Int)
+        n < 0 && throw(ArgumentError("n cannot be negative: $n"))
+        z = ncodeunits(s)
+        @boundscheck 0 ≤ i ≤ z || throw(BoundsError(s, i))
+        n == 0 && return thisind(s, i) == i ? i : throw(BoundsError(s, i))
+        while n > 0 && i < z
+            @inbounds n -= isvalid(s, i += 1)
+        end
+        return i + n
+    end
+    function Base.prevind(s::AbstractString, i::Int, n::Int)
+        n < 0 && throw(ArgumentError("n cannot be negative: $n"))
+        z = ncodeunits(s) + 1
+        @boundscheck 0 < i ≤ z || throw(BoundsError(s, i))
+        n == 0 && return thisind(s, i) == i ? i : throw(BoundsError(s, i))
+        while n > 0 && 1 < i
+            @inbounds n -= isvalid(s, i -= 1)
+        end
+        return i - n
+    end
+end
+
 if VERSION < v"0.7.0-DEV.5278"
     something() = throw(ArgumentError("No value arguments present"))
     something(x::Nothing, y...) = something(y...)
diff --git a/test/runtests.jl b/test/runtests.jl
index 73963fa47..7c8aee338 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1238,6 +1238,7 @@ end
 
 @test codeunits("foo") == [0x66,0x6f,0x6f] == codeunits(SubString("fooαβγ",1,3))
 @test ncodeunits("αβγ") == 6 == ncodeunits(SubString("fooαβγ",4,8))
+@test codeunit("foo") == codeunit(SubString("fooαβγ",1,3)) == UInt8
 
 # 0.7.0-DEV.3539
 @test nameof(Compat.Sys) == :Sys
@@ -1768,6 +1769,103 @@ end
 @test something(Some(2), 1) === 2
 @test something(nothing, Some(1)) === 1
 
+# julia#24999
+let s = "∀α>β:α+"
+    @test [length(s,i,j) for i=1:ncodeunits(s)+1, j=0:ncodeunits(s)] ==
+        [0 1 1 1 2 2 3 4 4 5 6 6 7; 0 0 0 0 1 1 2 3 3 4 5 5 6; 0 0 0 0 1 1 2 3 3 4 5 5 6; 0 0 0 0 1 1 2 3 3 4 5 5 6; 0 0 0 0 0 0 1 2 2 3 4 4 5; 0 0 0 0 0 0 1 2 2 3 4 4 5; 0 0 0 0 0 0 0 1 1 2 3 3 4; 0 0 0 0 0 0 0 0 0 1 2 2 3; 0 0 0 0 0 0 0 0 0 1 2 2 3; 0 0 0 0 0 0 0 0 0 0 1 1 2; 0 0 0 0 0 0 0 0 0 0 0 0 1; 0 0 0 0 0 0 0 0 0 0 0 0 1; 0 0 0 0 0 0 0 0 0 0 0 0 0]
+end
+@test_throws BoundsError length("hello", 1, -1)
+@test_throws BoundsError length("hellø", 1, -1)
+@test_throws BoundsError length("hello", 1, 10)
+@test_throws BoundsError length("hellø", 1, 10) == 9
+@test_throws BoundsError prevind("hello", 0, 1)
+@test_throws BoundsError prevind("hellø", 0, 1)
+@test nextind("hello", 0, 10) == 10
+# julia#24414
+let strs = Any["∀α>β:α+1>β", SubString("123∀α>β:α+1>β123", 4, 18)]
+    for s in strs
+        @test_throws BoundsError thisind(s, -2)
+        @test_throws BoundsError thisind(s, -1)
+        @test thisind(s, 0) == 0
+        @test thisind(s, 1) == 1
+        @test thisind(s, 2) == 1
+        @test thisind(s, 3) == 1
+        @test thisind(s, 4) == 4
+        @test thisind(s, 5) == 4
+        @test thisind(s, 6) == 6
+        @test thisind(s, 15) == 15
+        @test thisind(s, 16) == 15
+        @test thisind(s, 17) == 17
+        @test_throws BoundsError thisind(s, 18)
+        @test_throws BoundsError thisind(s, 19)
+    end
+end
+let strs = Any["", SubString("123", 2, 1)]
+    for s in strs
+        @test_throws BoundsError thisind(s, -1)
+        @test thisind(s, 0) == 0
+        @test thisind(s, 1) == 1
+        @test_throws BoundsError thisind(s, 2)
+    end
+end
+# prevind and nextind, julia#23805
+let s = "∀α>β:α+1>β"
+    @test_throws BoundsError prevind(s, 0, 0)
+    @test_throws BoundsError prevind(s, 0, 1)
+    @test prevind(s, 1, 1) == 0
+    @test prevind(s, 1, 0) == 1
+    @test prevind(s, 2, 1) == 1
+    @test prevind(s, 4, 1) == 1
+    @test prevind(s, 5, 1) == 4
+    @test prevind(s, 5, 2) == 1
+    @test prevind(s, 5, 3) == 0
+    @test prevind(s, 15, 1) == 14
+    @test prevind(s, 15, 2) == 13
+    @test prevind(s, 15, 3) == 12
+    @test prevind(s, 15, 4) == 10
+    @test prevind(s, 15, 10) == 0
+    @test prevind(s, 15, 9) == 1
+    @test prevind(s, 16, 1) == 15
+    @test prevind(s, 16, 2) == 14
+    @test prevind(s, 17, 1) == 15
+    @test prevind(s, 17, 2) == 14
+    @test_throws BoundsError prevind(s, 18, 0)
+    @test_throws BoundsError prevind(s, 18, 1)
+    @test_throws BoundsError nextind(s, -1, 0)
+    @test_throws BoundsError nextind(s, -1, 1)
+    @test nextind(s, 0, 2) == 4
+    @test nextind(s, 0, 20) == 26
+    @test nextind(s, 0, 10) == 15
+    @test nextind(s, 1, 1) == 4
+    @test nextind(s, 1, 2) == 6
+    @test nextind(s, 1, 9) == 15
+    @test nextind(s, 1, 10) == 17
+    @test nextind(s, 2, 1) == 4
+    @test nextind(s, 3, 1) == 4
+    @test nextind(s, 4, 1) == 6
+    @test nextind(s, 14, 1) == 15
+    @test nextind(s, 15, 1) == 17
+    @test nextind(s, 15, 2) == 18
+    @test nextind(s, 16, 1) == 17
+    @test nextind(s, 16, 2) == 18
+    @test nextind(s, 16, 3) == 19
+    @test_throws BoundsError nextind(s, 17, 0)
+    @test_throws BoundsError nextind(s, 17, 1)
+    for k in 0:ncodeunits(s)+1
+        n = p = k
+        for j in 1:40
+            if 1 ≤ p
+                p = prevind(s, p)
+                @test prevind(s, k, j) == p
+            end
+            if n ≤ ncodeunits(s)
+                n = nextind(s, n)
+                @test nextind(s, k, j) == n
+            end
+        end
+    end
+end
+
 # 0.7.0-DEV.5171
 let sep = Compat.Sys.iswindows() ? ';' : ':'
     withenv("PATH" => string(Compat.Sys.BINDIR, sep, get(ENV, "PATH", ""))) do