diff --git a/src/bidiag.jl b/src/bidiag.jl
index 13439ff9..52f72086 100644
--- a/src/bidiag.jl
+++ b/src/bidiag.jl
@@ -1215,26 +1215,22 @@ function _dibimul!(C::Bidiagonal, A::Diagonal, B::Bidiagonal, _add)
 end
 
 function mul(A::UpperOrUnitUpperTriangular, B::Bidiagonal)
-    TS = promote_op(matprod, eltype(A), eltype(B))
-    C = mul!(similar(A, TS, size(A)), A, B)
+    C = _mul(A, B)
     return B.uplo == 'U' ? UpperTriangular(C) : C
 end
 
 function mul(A::LowerOrUnitLowerTriangular, B::Bidiagonal)
-    TS = promote_op(matprod, eltype(A), eltype(B))
-    C = mul!(similar(A, TS, size(A)), A, B)
+    C = _mul(A, B)
     return B.uplo == 'L' ? LowerTriangular(C) : C
 end
 
 function mul(A::Bidiagonal, B::UpperOrUnitUpperTriangular)
-    TS = promote_op(matprod, eltype(A), eltype(B))
-    C = mul!(similar(B, TS, size(B)), A, B)
+    C = _mul(A, B)
     return A.uplo == 'U' ? UpperTriangular(C) : C
 end
 
 function mul(A::Bidiagonal, B::LowerOrUnitLowerTriangular)
-    TS = promote_op(matprod, eltype(A), eltype(B))
-    C = mul!(similar(B, TS, size(B)), A, B)
+    C = _mul(A, B)
     return A.uplo == 'L' ? LowerTriangular(C) : C
 end
 
diff --git a/src/matmul.jl b/src/matmul.jl
index efb9d0fe..2b2f7d81 100644
--- a/src/matmul.jl
+++ b/src/matmul.jl
@@ -51,11 +51,13 @@ end
 
 # Matrix-vector multiplication
 function (*)(A::StridedMaybeAdjOrTransMat{T}, x::StridedVector{S}) where {T<:BlasFloat,S<:Real}
+    matmul_size_check(size(A), size(x))
     TS = promote_op(matprod, T, S)
     y = isconcretetype(TS) ? convert(AbstractVector{TS}, x) : x
     mul!(similar(x, TS, size(A,1)), A, y)
 end
 function (*)(A::AbstractMatrix{T}, x::AbstractVector{S}) where {T,S}
+    matmul_size_check(size(A), size(x))
     TS = promote_op(matprod, T, S)
     mul!(similar(x, TS, axes(A,1)), A, x)
 end
@@ -113,7 +115,10 @@ julia> [1 1; 0 1] * [1 0; 1 1]
 """
 (*)(A::AbstractMatrix, B::AbstractMatrix) = mul(A, B)
 # we add an extra level of indirection to avoid ambiguities in *
-function mul(A::AbstractMatrix, B::AbstractMatrix)
+# We also define the core functionality within _mul to reuse the code elsewhere
+mul(A::AbstractMatrix, B::AbstractMatrix) = _mul(A, B)
+function _mul(A::AbstractMatrix, B::AbstractMatrix)
+    matmul_size_check(size(A), size(B))
     TS = promote_op(matprod, eltype(A), eltype(B))
     mul!(matprod_dest(A, B, TS), A, B)
 end
diff --git a/src/symmetric.jl b/src/symmetric.jl
index 09819325..d063bb44 100644
--- a/src/symmetric.jl
+++ b/src/symmetric.jl
@@ -707,12 +707,14 @@ end
 mul(A::HermOrSym, B::HermOrSym) = A * copyto!(similar(parent(B)), B)
 # catch a few potential BLAS-cases
 function mul(A::HermOrSym{<:BlasFloat,<:StridedMatrix}, B::AdjOrTrans{<:BlasFloat,<:StridedMatrix})
+    matmul_size_check(size(A), size(B))
     T = promote_type(eltype(A), eltype(B))
     mul!(similar(B, T, (size(A, 1), size(B, 2))),
             convert(AbstractMatrix{T}, A),
             copy_oftype(B, T)) # make sure the AdjOrTrans wrapper is resolved
 end
 function mul(A::AdjOrTrans{<:BlasFloat,<:StridedMatrix}, B::HermOrSym{<:BlasFloat,<:StridedMatrix})
+    matmul_size_check(size(A), size(B))
     T = promote_type(eltype(A), eltype(B))
     mul!(similar(B, T, (size(A, 1), size(B, 2))),
             copy_oftype(A, T), # make sure the AdjOrTrans wrapper is resolved