diff --git a/src/transfer-functions/integration.jl b/src/transfer-functions/integration.jl
index f5a6184d..bd000cb6 100644
--- a/src/transfer-functions/integration.jl
+++ b/src/transfer-functions/integration.jl
@@ -18,10 +18,10 @@ _integration_setup(
     g_grid_upscale = 2,
 ) = IntegrationSetup(h, time, integrand, pure_radial, alloc_segbuf(T), g_grid_upscale)
 
-function _g_fine_grid_iterate(setup::IntegrationSetup, lo, hi)
-    Δ = (hi - lo) / setup.g_grid_upscale
-    lows = range(lo, hi - Δ, setup.g_grid_upscale)
-    highs = range(lo + Δ, hi, setup.g_grid_upscale)
+function _g_fine_grid_iterate(upscale, lo, hi)
+    Δ = (hi - lo) / upscale
+    lows = range(lo, hi - Δ, upscale)
+    highs = range(lo + Δ, hi, upscale)
     zip(lows, highs)
 end
 
@@ -249,7 +249,8 @@ function _integrate_transfer_problem!(
             glo = g_grid[j]
             ghi = g_grid[j+1]
             flux_contrib = zero(eltype(output))
-            for (g_fine_lo, g_fine_hi) in _g_fine_grid_iterate(setup, glo, ghi)
+            for (g_fine_lo, g_fine_hi) in
+                _g_fine_grid_iterate(setup.g_grid_upscale, glo, ghi)
                 k = integrate_bin(closures, _both_branches(closures), g_fine_lo, g_fine_hi)
                 flux_contrib += k
             end
@@ -278,26 +279,28 @@ function _integrate_transfer_problem!(
         t_source_disc = setup.time(rₑ)
 
         @inbounds for j in eachindex(g_grid_view)
-            glo = clamp(g_grid[j], closures.branch.gmin, closures.branch.gmax)
-            ghi = clamp(g_grid[j+1], closures.branch.gmin, closures.branch.gmax)
+            g_grid_low = clamp(g_grid[j], closures.branch.gmin, closures.branch.gmax)
+            g_grid_hi = clamp(g_grid[j+1], closures.branch.gmin, closures.branch.gmax)
             # skip if bin not relevant
-            if glo == ghi
+            if g_grid_low == g_grid_hi
                 continue
             end
-            k1 = integrate_bin(closures, _lower_branch(closures), glo, ghi)
-            k2 = integrate_bin(closures, _upper_branch(closures), glo, ghi)
-
-            # find which bin to dump in
-            t_lower_branch, t_upper_branch = _time_bins(closures, glo, ghi)
-            i1 = searchsortedfirst(t_grid, t_lower_branch + t_source_disc)
-            i2 = searchsortedfirst(t_grid, t_upper_branch + t_source_disc)
-
-            imax = lastindex(t_grid)
-            if i1 <= imax
-                output[j, i1] += k1 * θ
-            end
-            if i2 <= imax
-                output[j, i2] += k2 * θ
+            for (glo, ghi) in
+                _g_fine_grid_iterate(setup.g_grid_upscale, g_grid_low, g_grid_hi)
+                k1 = integrate_bin(closures, _lower_branch(closures), glo, ghi)
+                k2 = integrate_bin(closures, _upper_branch(closures), glo, ghi)
+                # find which bin to dump in
+                t_lower_branch, t_upper_branch = _time_bins(closures, glo, ghi)
+                i1 = searchsortedfirst(t_grid, t_lower_branch + t_source_disc)
+                i2 = searchsortedfirst(t_grid, t_upper_branch + t_source_disc)
+
+                imax = lastindex(t_grid)
+                if i1 <= imax
+                    output[j, i1] += k1 * θ
+                end
+                if i2 <= imax
+                    output[j, i2] += k2 * θ
+                end
             end
         end
     end