diff --git a/ext/VectorInterfaceEnzymeExt.jl b/ext/VectorInterfaceEnzymeExt.jl
index a61c775..4d4045f 100644
--- a/ext/VectorInterfaceEnzymeExt.jl
+++ b/ext/VectorInterfaceEnzymeExt.jl
@@ -3,28 +3,11 @@ module VectorInterfaceEnzymeExt
 # COV_EXCL_START
 # Enzyme rules aren't reachable by coverage
 using VectorInterface
+using VectorInterface: project_scalar, project_add!
 using Enzyme
 using Enzyme.EnzymeCore
 using Enzyme.EnzymeCore: EnzymeRules
 
-function project_add!(C, A, α)
-    TC = Base.promote_op(+, scalartype(A), scalartype(α))
-    return if !(TC <: Real) && scalartype(C) <: Real
-        add!(C, real(add!(zerovector(C, TC), A, α)))
-    else
-        add!(C, A, α)
-    end
-end
-
-"""
-    project_scalar(x::Number, dx::Number)
-
-Project a computed tangent `dx` onto the correct tangent type for `x`.
-For example, we might compute a complex `dx` but only require the real part.
-"""
-project_scalar(x::Number, dx::Number) = oftype(x, dx)
-project_scalar(x::Real, dx::Complex) = project_scalar(x, real(dx))
-
 function EnzymeRules.augmented_primal(
         config::EnzymeRules.RevConfigWidth{1},
         func::Const{typeof(scale!)},
diff --git a/ext/VectorInterfaceMooncakeExt.jl b/ext/VectorInterfaceMooncakeExt.jl
index 00ad349..084c7b1 100644
--- a/ext/VectorInterfaceMooncakeExt.jl
+++ b/ext/VectorInterfaceMooncakeExt.jl
@@ -1,31 +1,12 @@
 module VectorInterfaceMooncakeExt
 
 using VectorInterface
+using VectorInterface: project_scalar, project_add!
 using Mooncake
 using Mooncake: @is_primitive, DefaultCtx,
     NoFData, NoRData, NoTangent,
     CoDual, Dual, arrayify, primal, extract
 
-# Projection
-# ----------
-"""
-    project_scalar(x::Number, dx::Number)
-
-Project a computed tangent `dx` onto the correct tangent type for `x`.
-For example, we might compute a complex `dx` but only require the real part.
-"""
-project_scalar(x::Number, dx::Number) = oftype(x, dx)
-project_scalar(x::Real, dx::Complex) = project_scalar(x, real(dx))
-
-function project_add!(C, A, α)
-    TC = Base.promote_op(+, scalartype(A), scalartype(α))
-    return if !(TC <: Real) && scalartype(C) <: Real
-        add!(C, real(add!(zerovector(C, TC), A, α)))
-    else
-        add!(C, A, α)
-    end
-end
-
 _needs_tangent(x) = _needs_tangent(typeof(x))
 _needs_tangent(::Type{T}) where {T <: Number} =
     Mooncake.rdata_type(Mooncake.tangent_type(T)) !== NoRData
diff --git a/src/VectorInterface.jl b/src/VectorInterface.jl
index df0e684..85088a1 100644
--- a/src/VectorInterface.jl
+++ b/src/VectorInterface.jl
@@ -48,4 +48,7 @@ include("fallbacks.jl")
 # Minimal vector type for testing
 include("minimalvec.jl")
 
+# Common AD helper methods
+include("ad.jl")
+
 end
diff --git a/src/ad.jl b/src/ad.jl
new file mode 100644
index 0000000..e5f86e1
--- /dev/null
+++ b/src/ad.jl
@@ -0,0 +1,17 @@
+function project_add!(C, A, α)
+    TC = Base.promote_op(+, scalartype(A), scalartype(α))
+    return if !(TC <: Real) && scalartype(C) <: Real
+        add!(C, real(add!(zerovector(C, TC), A, α)))
+    else
+        add!(C, A, α)
+    end
+end
+
+"""
+    project_scalar(x::Number, dx::Number)
+
+Project a computed tangent `dx` onto the correct tangent type for `x`.
+For example, we might compute a complex `dx` but only require the real part.
+"""
+project_scalar(x::Number, dx::Number) = oftype(x, dx)
+project_scalar(x::Real, dx::Complex) = project_scalar(x, real(dx))