diff --git a/src/pdiagmat.jl b/src/pdiagmat.jl
index 8c4887c..6edf925 100644
--- a/src/pdiagmat.jl
+++ b/src/pdiagmat.jl
@@ -28,7 +28,7 @@ diag(a::PDiagMat) = copy(a.diag)
 
 function pdadd!(r::Matrix, a::Matrix, b::PDiagMat, c)
     @check_argdims size(r) == size(a) == size(b)
-    if is(r, a)
+    if r === a
         _adddiag!(r, b.diag, c)
     else
         _adddiag!(copy!(r, a), b.diag, c)
diff --git a/src/scalmat.jl b/src/scalmat.jl
index b111b7f..d2105c2 100644
--- a/src/scalmat.jl
+++ b/src/scalmat.jl
@@ -23,7 +23,7 @@ diag(a::ScalMat) = fill(a.value, a.dim)
 
 function pdadd!(r::Matrix, a::Matrix, b::ScalMat, c)
     @check_argdims size(r) == size(a) == size(b)
-    if is(r, a)
+    if r === a
         _adddiag!(r, b.value * c)
     else
         _adddiag!(copy!(r, a), b.value * c)
diff --git a/src/testutils.jl b/src/testutils.jl
index 0311d58..34bb82c 100644
--- a/src/testutils.jl
+++ b/src/testutils.jl
@@ -115,7 +115,7 @@ function pdtest_add(C::AbstractPDMat, Cmat::Matrix, verbose::Int)
     _pdt(verbose, "add_scal!")
     R = M + Cmat * convert(eltype(C),2)
     Mr = pdadd!(M, C, convert(eltype(C),2))
-    @test is(Mr, M)
+    @test Mr === M
     @test_approx_eq Mr R
 end
 
diff --git a/src/utils.jl b/src/utils.jl
index 1ce56fc..a336b9c 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -7,7 +7,7 @@ macro check_argdims(cond)
     end
 end
 
-_rcopy!(r::StridedVecOrMat, x::StridedVecOrMat) = (is(r, x) || copy!(r, x); r)
+_rcopy!(r::StridedVecOrMat, x::StridedVecOrMat) = (r === x || copy!(r, x); r)
 
 
 @compat function _addscal!(r::Matrix, a::Matrix, b::Union{Matrix, SparseMatrixCSC}, c::Real)