diff --git a/src/subtype.c b/src/subtype.c
index 8eb6313954263..b4410ee911d6b 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -520,11 +520,9 @@ static int is_leaf_bound(jl_value_t *v)
     return !jl_is_type(v) && !jl_is_typevar(v);
 }
 
-static int is_leaf_typevar(jl_value_t *v)
+static int is_leaf_typevar(jl_tvar_t *v)
 {
-    if (jl_is_typevar(v))
-        return is_leaf_typevar(((jl_tvar_t*)v)->lb);
-    return is_leaf_bound(v);
+    return is_leaf_bound(v->lb);
 }
 
 static jl_value_t *widen_Type(jl_value_t *t)
@@ -630,7 +628,7 @@ static int subtype_unionall(jl_value_t *t, jl_unionall_t *u, jl_stenv_t *e, int8
     // !( Tuple{Int, String} <: Tuple{T, T} where T)
     // Then check concreteness by checking that the lower bound is not an abstract type.
     int diagonal = !vb.occurs_inv && vb.occurs_cov > 1;
-    if (ans && (vb.concrete || (diagonal && is_leaf_typevar((jl_value_t*)u->var)))) {
+    if (ans && (vb.concrete || (diagonal && is_leaf_typevar(u->var)))) {
         if (vb.concrete && !diagonal && !is_leaf_bound(vb.ub)) {
             // a non-diagonal var can only be a subtype of a diagonal var if its
             // upper bound is concrete.
@@ -1559,7 +1557,7 @@ static jl_value_t *intersect_unionall_(jl_value_t *t, jl_unionall_t *u, jl_stenv
     else {
         res = intersect(u->body, t, e, param);
     }
-    vb->concrete |= (!vb->occurs_inv && vb->occurs_cov > 1 && is_leaf_typevar((jl_value_t*)u->var));
+    vb->concrete |= (!vb->occurs_inv && vb->occurs_cov > 1 && is_leaf_typevar(u->var));
 
     // handle the "diagonal dispatch" rule, which says that a type var occurring more
     // than once, and only in covariant position, is constrained to concrete types. E.g.
@@ -2027,11 +2025,11 @@ static jl_value_t *intersect(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, int pa
                 if (ii == jl_bottom_type) return jl_bottom_type;
                 if (jl_is_typevar(xp1)) {
                     jl_varbinding_t *xb = lookup(e, (jl_tvar_t*)xp1);
-                    if (xb && is_leaf_typevar((jl_value_t*)xb->var)) xb->concrete = 1;
+                    if (xb && is_leaf_typevar(xb->var)) xb->concrete = 1;
                 }
                 if (jl_is_typevar(yp1)) {
                     jl_varbinding_t *yb = lookup(e, (jl_tvar_t*)yp1);
-                    if (yb && is_leaf_typevar((jl_value_t*)yb->var)) yb->concrete = 1;
+                    if (yb && is_leaf_typevar(yb->var)) yb->concrete = 1;
                 }
                 JL_GC_PUSH2(&ii, &i2);
                 // Vararg{T,N} <: Vararg{T2,N2}; equate N and N2
diff --git a/test/subtype.jl b/test/subtype.jl
index 69150ee6fb34c..f62418aa57e67 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -86,7 +86,7 @@ function test_diagonal()
     @test !issub(Tuple{Integer,Integer}, @UnionAll T Tuple{T,T})
     @test issub(Tuple{Integer,Int}, (@UnionAll T @UnionAll S<:T Tuple{T,S}))
     @test issub(Tuple{Integer,Int}, (@UnionAll T @UnionAll T<:S<:T Tuple{T,S}))
-    @test !issub(Tuple{Integer,Int,Int}, (@UnionAll T @UnionAll T<:S<:T Tuple{T,S,S}))
+    @test issub(Tuple{Integer,Int,Int}, (@UnionAll T @UnionAll T<:S<:T Tuple{T,S,S}))
 
     @test issub_strict((@UnionAll R Tuple{R,R}),
                        (@UnionAll T @UnionAll S Tuple{T,S}))
@@ -132,6 +132,8 @@ function test_diagonal()
     @test  issub(Tuple{Tuple{T, T} where T>:Int}, Tuple{Tuple{T, T} where T>:Int})
     @test  issub(Tuple{Tuple{T, T} where T>:Int}, Tuple{Tuple{T, T}} where T>:Int)
     @test  issub(Tuple{Tuple{T, T}} where T>:Int, Tuple{Tuple{T, T} where T>:Int})
+    @test  issub(Vector{Tuple{T, T} where Number<:T<:Number},
+                 Vector{Tuple{Number, Number}})
 end
 
 # level 3: UnionAll
@@ -1259,3 +1261,12 @@ end
 let (t, e) = intersection_env(Tuple{Union{Int,Int8}}, Tuple{T} where T)
     @test e[1] isa TypeVar
 end
+
+# issue #26453
+@test (Tuple{A,A,Number} where A>:Number) <: Tuple{T,T,S} where T>:S where S
+@test (Tuple{T,T} where {S,T>:S}) == (Tuple{T,T} where {S,T>:S})
+f26453(x::T,y::T) where {S,T>:S} = 0
+@test f26453(1,2) == 0
+@test f26453(1,"") == 0
+g26453(x::T,y::T) where {S,T>:S} = T
+@test_throws UndefVarError(:T) g26453(1,1)