diff --git a/stdlib/LinearAlgebra/src/matmul.jl b/stdlib/LinearAlgebra/src/matmul.jl
index 30b410bbff6ef..a453078711d1a 100644
--- a/stdlib/LinearAlgebra/src/matmul.jl
+++ b/stdlib/LinearAlgebra/src/matmul.jl
@@ -152,15 +152,23 @@ function (*)(A::AbstractMatrix, B::AbstractMatrix)
     TS = promote_op(matprod, eltype(A), eltype(B))
     mul!(similar(B, TS, (size(A,1), size(B,2))), A, B)
 end
-@inline mul!(C::StridedMatrix{T}, A::StridedVecOrMat{T}, B::StridedVecOrMat{T},
-             alpha::Union{T, Bool}, beta::Union{T, Bool}) where {T<:BlasFloat} =
-    gemm_wrapper!(C, 'N', 'N', A, B, MulAddMul(alpha, beta))
+
+@inline function mul!(C::StridedMatrix{T}, A::StridedVecOrMat{T}, B::StridedVecOrMat{T},
+                      α::Number, β::Number) where {T<:BlasFloat}
+    alpha, beta = promote(α, β, zero(T))
+    if alpha isa T && beta isa T
+        return gemm_wrapper!(C, 'N', 'N', A, B, MulAddMul(alpha, beta))
+    else
+        return generic_matmatmul!(C, 'N', 'N', A, B, MulAddMul(α, β))
+    end
+end
+
 # Complex Matrix times real matrix: We use that it is generally faster to reinterpret the
 # first matrix as a real matrix and carry out real matrix matrix multiply
 for elty in (Float32,Float64)
     @eval begin
         @inline function mul!(C::StridedMatrix{Complex{$elty}}, A::StridedVecOrMat{Complex{$elty}}, B::StridedVecOrMat{$elty},
-                         alpha::Union{$elty, Bool}, beta::Union{$elty, Bool})
+                              alpha::Real, beta::Real)
             Afl = reinterpret($elty, A)
             Cfl = reinterpret($elty, C)
             mul!(Cfl, Afl, B, alpha, beta)
diff --git a/stdlib/LinearAlgebra/test/matmul.jl b/stdlib/LinearAlgebra/test/matmul.jl
index 794ec672297a4..46dc2aea3a903 100644
--- a/stdlib/LinearAlgebra/test/matmul.jl
+++ b/stdlib/LinearAlgebra/test/matmul.jl
@@ -586,7 +586,7 @@ end
     A = rand(n, n)
     B = rand(n, n)
     C = zeros(n, n)
-    mul!(C, A, B, -1, 0)
+    mul!(C, A, B, -1 + 0im, 0)
     D = -A * B
     @test D ≈ C