diff --git a/base/array.jl b/base/array.jl
index ca89fc1571cbe..cdffc3798bf5d 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -244,7 +244,7 @@ segfault your program, in the same manner as C.
 function unsafe_copyto!(dest::Ptr{T}, src::Ptr{T}, n) where T
     # Do not use this to copy data between pointer arrays.
     # It can't be made safe no matter how carefully you checked.
-    ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, UInt),
+    ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t),
           dest, src, n * aligned_sizeof(T))
     return dest
 end
@@ -268,13 +268,13 @@ function unsafe_copyto!(dest::Array{T}, doffs, src::Array{T}, soffs, n) where T
         ccall(:jl_array_ptr_copy, Cvoid, (Any, Ptr{Cvoid}, Any, Ptr{Cvoid}, Int),
               dest, destp, src, srcp, n)
     elseif isbitstype(T)
-        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, UInt),
+        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t),
               destp, srcp, n * aligned_sizeof(T))
     elseif isbitsunion(T)
-        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, UInt),
+        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t),
               destp, srcp, n * aligned_sizeof(T))
         # copy selector bytes
-        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, UInt),
+        ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t),
               ccall(:jl_array_typetagdata, Ptr{UInt8}, (Any,), dest) + doffs - 1,
               ccall(:jl_array_typetagdata, Ptr{UInt8}, (Any,), src) + soffs - 1,
               n)
diff --git a/base/ryu/utils.jl b/base/ryu/utils.jl
index 46a88c0ef9d9f..49b0856f4c6f1 100644
--- a/base/ryu/utils.jl
+++ b/base/ryu/utils.jl
@@ -1,8 +1,8 @@
 const MANTISSA_MASK = Base.significand_mask(Float64)
 const EXP_MASK = Base.exponent_mask(Float64) >> Base.significand_bits(Float64)
 
-memcpy(d, doff, s, soff, n) = ccall(:memcpy, Cvoid, (Ptr{Cvoid}, Ptr{Cvoid}, Int), d + doff - 1, s + soff - 1, n)
-memmove(d, doff, s, soff, n) = ccall(:memmove, Cvoid, (Ptr{Cvoid}, Ptr{Cvoid}, Int), d + doff - 1, s + soff - 1, n)
+memcpy(d, doff, s, soff, n) = (ccall(:memcpy, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t), d + doff - 1, s + soff - 1, n); nothing)
+memmove(d, doff, s, soff, n) = (ccall(:memmove, Ptr{Cvoid}, (Ptr{Cvoid}, Ptr{Cvoid}, Csize_t), d + doff - 1, s + soff - 1, n); nothing)
 
 # Note: these are smaller than the values given in Figure 4 from the paper
 # see https://github.com/ulfjack/ryu/issues/119