diff --git a/base/Base.jl b/base/Base.jl
index 3b53173827610..5c3798563c2c0 100644
--- a/base/Base.jl
+++ b/base/Base.jl
@@ -145,7 +145,7 @@ include("abstractarraymath.jl")
 include("arraymath.jl")
 
 # SIMD loops
-@pure sizeof(s::String) = Core.sizeof(s)  # needed by gensym as called from simdloop
+sizeof(s::String) = Core.sizeof(s)  # needed by gensym as called from simdloop
 include("simdloop.jl")
 using .SimdLoop
 
diff --git a/base/strings/string.jl b/base/strings/string.jl
index 99b706fc27ced..847ca0d1991c4 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -95,7 +95,7 @@ String(s::CodeUnits{UInt8,String}) = s.s
 pointer(s::String) = unsafe_convert(Ptr{UInt8}, s)
 pointer(s::String, i::Integer) = pointer(s) + Int(i)::Int - 1
 
-@pure ncodeunits(s::String) = Core.sizeof(s)
+ncodeunits(s::String) = Core.sizeof(s)
 codeunit(s::String) = UInt8
 
 @inline function codeunit(s::String, i::Integer)