diff --git a/ext/DiffEqBaseForwardDiffExt.jl b/ext/DiffEqBaseForwardDiffExt.jl
index 0fd81e0dc..fe941e8de 100644
--- a/ext/DiffEqBaseForwardDiffExt.jl
+++ b/ext/DiffEqBaseForwardDiffExt.jl
@@ -4,11 +4,11 @@ using DiffEqBase, ForwardDiff
 using DiffEqBase.ArrayInterface
 using DiffEqBase: Void, FunctionWrappersWrappers, OrdinaryDiffEqTag,
                   AbstractTimeseriesSolution,
-                  RecursiveArrayTools, reduce_tup, _promote_tspan, has_continuous_callback
+                  RecursiveArrayTools
 import DiffEqBase: hasdualpromote, wrapfun_oop, wrapfun_iip, prob2dtmin,
                    promote_tspan, ODE_DEFAULT_NORM,
                    InternalITP, nextfloat_tdir
-import SciMLBase: isdualtype, DualEltypeChecker, sse, __sum
+import SciMLBase: isdualtype, DualEltypeChecker, sse, __sum, promote_tspan, has_continuous_callback
 
 const dualT = ForwardDiff.Dual{ForwardDiff.Tag{OrdinaryDiffEqTag, Float64}, Float64, 1}
 dualgen(::Type{T}) where {T} = ForwardDiff.Dual{ForwardDiff.Tag{OrdinaryDiffEqTag, T}, T, 1}
diff --git a/src/solve.jl b/src/solve.jl
index 55b4a636f..846593749 100644
--- a/src/solve.jl
+++ b/src/solve.jl
@@ -828,17 +828,6 @@ function get_concrete_problem(prob::DDEProblem, isadapt; kwargs...)
     remake(prob; u0 = u0, tspan = tspan, p = p, constant_lags = constant_lags)
 end
 
-# Most are extensions
-promote_tspan(u0, p, tspan, prob, kwargs) = _promote_tspan(tspan, kwargs)
-function _promote_tspan(tspan, kwargs)
-    if (dt = get(kwargs, :dt, nothing)) !== nothing
-        tspan1, tspan2, _ = promote(tspan..., dt)
-        return (tspan1, tspan2)
-    else
-        return tspan
-    end
-end
-
 function promote_f(f::F, ::Val{specialize}, u0, p, t) where {F, specialize}
     # Ensure our jacobian will be of the same type as u0
     uElType = u0 === nothing ? Float64 : eltype(u0)