diff --git a/src/operators.jl b/src/operators.jl
index a0b8d033..fa8f55cc 100644
--- a/src/operators.jl
+++ b/src/operators.jl
@@ -91,7 +91,9 @@ function polynomial_merge!(
     combine::F6,
     keep::F7,
     resize::F8,
-) where {F1,F2,F3,F4,F5,F6,F7,F8}
+    ::Type{term_type} = n1 > 0 ? typeof(get1(1)) :
+                        n2 > 0 ? typeof(get2(1)) : Nothing,
+) where {F1,F2,F3,F4,F5,F6,F7,F8,term_type}
     buffer = nothing
     i = j = k = 1
     # Invariant:
@@ -109,7 +111,7 @@ function polynomial_merge!(
             if k == i
                 t0 = get1(i)
                 if buffer === nothing
-                    buffer = DataStructures.Queue{typeof(t0)}()
+                    buffer = DataStructures.Queue{term_type}()
                 end
                 push!(buffer, t0)
                 i += 1
diff --git a/test/commutative/complex.jl b/test/commutative/complex.jl
index a69e4b61..2765822b 100644
--- a/test/commutative/complex.jl
+++ b/test/commutative/complex.jl
@@ -6,7 +6,7 @@
     @test !isconj(a)
     @test ordinary_variable(a) == a
     @test conj(a) == real(a) == a
-    @test_broken iszero(imag(a)) # no iszero for MA.Zero
+    @test iszero(imag(a))
     @test isreal(a^3 + 5a^2 + 4a)
     @test !isreal(a^3 + 5im * a^2 + 4a)
 
diff --git a/test/commutative/gcd.jl b/test/commutative/gcd.jl
index c5c43a00..fe7c043a 100644
--- a/test/commutative/gcd.jl
+++ b/test/commutative/gcd.jl
@@ -291,14 +291,15 @@ end
             end
         end
     end
-    @testset "Non-concrete polynomial GCD" begin
-        Mod.@polyvar p q
-        p1 = MP.polynomial(p^2 + q^2, Number)
-        p2 = MP.polynomial(p * q, Number)
-        g = @inferred gcd(p1, p2)
-        @test isone(g)
+    if nameof(Mod) == :DynamicPolynomials
+        @testset "Non-concrete polynomial GCD" begin
+            Mod.@polyvar p q
+            p1 = MP.polynomial(p^2 + q^2, Number)
+            p2 = MP.polynomial(p * q, Number)
+            g = @inferred gcd(p1, p2)
+            @test isone(g)
+        end
     end
-
     @testset "Complex coefficient GCD" begin
         Mod.@polyvar p q
         p1 = MP.polynomial(p^2 + q^2, ComplexF64)