diff --git a/Project.toml b/Project.toml
index d59d073..bb189e6 100644
--- a/Project.toml
+++ b/Project.toml
@@ -6,9 +6,6 @@ authors = ["Tamas K. Papp <tkpapp@gmail.com>"]
 Parameters = "d96e819e-fc66-5662-9728-84c9c7592b0a"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 
-[compat]
-StaticArrays = "^0.9, ^0.10"
-
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
diff --git a/src/StrFs.jl b/src/StrFs.jl
index abfe3d0..08dea50 100644
--- a/src/StrFs.jl
+++ b/src/StrFs.jl
@@ -6,7 +6,8 @@ using StaticArrays: SVector
 using Parameters
 
 import Base: sizeof, read, write, isless, cmp, ==, typemin, repeat, promote_rule, show,
-    codeunit, hash, length
+    codeunit, hash, length, ncodeunits, codeunit, codeunits, lastindex, firstindex,
+    isvalid
 
 """
     StrF{S}(::String)
@@ -120,6 +121,18 @@ typemin(::StrF{S}) where S = StrF(zeros(SVector{S}))
 
 length(str::StrF) = length(String(str)) # TODO improve
 
+ncodeunits(s::StrF) = ncodeunits(String(s)) # TODO improve
+
+codeunit(s::StrF, i::Integer) = codeunit(String(s), i) # TODO improve
+
+codeunits(s::StrF) = codeunits(String(s)) # TODO improve
+
+lastindex(s::StrF) = lastindex(String(s)) # TODO improve
+
+firstindex(s::StrF) = firstindex(String(s)) # TODO improve
+
+isvalid(s::StrF, i::Integer) = isvalid(String(s), i) # TODO improve
+
 function repeat(str::StrF{S}, ::Val{n}) where {S, n}
     @unpack bytes = str
     s = sizeof(str)