diff --git a/mat/doc.go b/mat/doc.go
index 129444f9..2cc91001 100644
--- a/mat/doc.go
+++ b/mat/doc.go
@@ -164,8 +164,6 @@
 //    the value has been untransposed if necessary.
 //
 // mat will not attempt to detect element overlap if the input does not implement a
-// Raw method, or if the Raw method differs from that of the receiver except when a
-// conversion has occurred through a mat API function. Method behavior is undefined
-// if there is undetected overlap.
+// Raw method. Method behavior is undefined if there is undetected overlap.
 //
 package mat // import "gonum.org/v1/gonum/mat"
diff --git a/mat/shadow.go b/mat/shadow.go
index 5749241a..bcc55d6a 100644
--- a/mat/shadow.go
+++ b/mat/shadow.go
@@ -70,8 +70,8 @@ func (m *Dense) checkOverlap(a blas64.General) bool {
 	return checkOverlap(m.RawMatrix(), a)
 }
 
-func (s *SymDense) checkOverlap(a blas64.Symmetric) bool {
-	return checkOverlap(generalFromSymmetric(s.RawSymmetric()), generalFromSymmetric(a))
+func (s *SymDense) checkOverlap(a blas64.General) bool {
+	return checkOverlap(generalFromSymmetric(s.RawSymmetric()), a)
 }
 
 // generalFromSymmetric returns a blas64.General with the backing
@@ -85,8 +85,8 @@ func generalFromSymmetric(a blas64.Symmetric) blas64.General {
 	}
 }
 
-func (t *TriDense) checkOverlap(a blas64.Triangular) bool {
-	return checkOverlap(generalFromTriangular(t.RawTriangular()), generalFromTriangular(a))
+func (t *TriDense) checkOverlap(a blas64.General) bool {
+	return checkOverlap(generalFromTriangular(t.RawTriangular()), a)
 }
 
 // generalFromTriangular returns a blas64.General with the backing
diff --git a/mat/symmetric.go b/mat/symmetric.go
index 873f5f34..9ef2b3ed 100644
--- a/mat/symmetric.go
+++ b/mat/symmetric.go
@@ -179,10 +179,10 @@ func (s *SymDense) AddSym(a, b Symmetric) {
 		if b, ok := b.(RawSymmetricer); ok {
 			amat, bmat := a.RawSymmetric(), b.RawSymmetric()
 			if s != a {
-				s.checkOverlap(amat)
+				s.checkOverlap(generalFromSymmetric(amat))
 			}
 			if s != b {
-				s.checkOverlap(bmat)
+				s.checkOverlap(generalFromSymmetric(bmat))
 			}
 			for i := 0; i < n; i++ {
 				btmp := bmat.Data[i*bmat.Stride+i : i*bmat.Stride+n]
@@ -240,7 +240,7 @@ func (s *SymDense) SymRankOne(a Symmetric, alpha float64, x *VecDense) {
 	s.reuseAs(n)
 	if s != a {
 		if rs, ok := a.(RawSymmetricer); ok {
-			s.checkOverlap(rs.RawSymmetric())
+			s.checkOverlap(generalFromSymmetric(rs.RawSymmetric()))
 		}
 		s.CopySym(a)
 	}
@@ -266,7 +266,7 @@ func (s *SymDense) SymRankK(a Symmetric, alpha float64, x Matrix) {
 	}
 	if a != s {
 		if rs, ok := a.(RawSymmetricer); ok {
-			s.checkOverlap(rs.RawSymmetric())
+			s.checkOverlap(generalFromSymmetric(rs.RawSymmetric()))
 		}
 		s.reuseAs(n)
 		s.CopySym(a)
@@ -304,8 +304,13 @@ func (s *SymDense) SymOuterK(alpha float64, x Matrix) {
 			s.CopySym(w)
 			putWorkspaceSym(w)
 		} else {
-			if rs, ok := x.(RawSymmetricer); ok {
-				s.checkOverlap(rs.RawSymmetric())
+			switch r := x.(type) {
+			case RawMatrixer:
+				s.checkOverlap(r.RawMatrix())
+			case RawSymmetricer:
+				s.checkOverlap(generalFromSymmetric(r.RawSymmetric()))
+			case RawTriangular:
+				s.checkOverlap(generalFromTriangular(r.RawTriangular()))
 			}
 			// Only zero the upper triangle.
 			for i := 0; i < n; i++ {
@@ -337,7 +342,7 @@ func (s *SymDense) RankTwo(a Symmetric, alpha float64, x, y *VecDense) {
 	w.reuseAs(n)
 	if s != a {
 		if rs, ok := a.(RawSymmetricer); ok {
-			s.checkOverlap(rs.RawSymmetric())
+			s.checkOverlap(generalFromSymmetric(rs.RawSymmetric()))
 		}
 		w.CopySym(a)
 	}
@@ -352,7 +357,7 @@ func (s *SymDense) ScaleSym(f float64, a Symmetric) {
 	if a, ok := a.(RawSymmetricer); ok {
 		amat := a.RawSymmetric()
 		if s != a {
-			s.checkOverlap(amat)
+			s.checkOverlap(generalFromSymmetric(amat))
 		}
 		for i := 0; i < n; i++ {
 			for j := i; j < n; j++ {
@@ -386,7 +391,7 @@ func (s *SymDense) SubsetSym(a Symmetric, set []int) {
 	if a, ok := a.(RawSymmetricer); ok {
 		raw := a.RawSymmetric()
 		if s != a {
-			s.checkOverlap(raw)
+			s.checkOverlap(generalFromSymmetric(raw))
 		}
 		for i := 0; i < n; i++ {
 			ssub := s.mat.Data[i*s.mat.Stride : i*s.mat.Stride+n]
diff --git a/mat/triangular.go b/mat/triangular.go
index cb38d5e5..c49e0078 100644
--- a/mat/triangular.go
+++ b/mat/triangular.go
@@ -344,7 +344,7 @@ func (t *TriDense) Copy(a Matrix) (r, c int) {
 // avoided where possible, for example by using the Solve routines.
 func (t *TriDense) InverseTri(a Triangular) error {
 	if rt, ok := a.(RawTriangular); ok {
-		t.checkOverlap(rt.RawTriangular())
+		t.checkOverlap(generalFromTriangular(rt.RawTriangular()))
 	}
 	n, _ := a.Triangle()
 	t.reuseAs(a.Triangle())