diff --git a/src/common_models/market_bid_plumbing.jl b/src/common_models/market_bid_plumbing.jl
index b2ae44d..6006b8f 100644
--- a/src/common_models/market_bid_plumbing.jl
+++ b/src/common_models/market_bid_plumbing.jl
@@ -234,7 +234,7 @@ function _validate_occ_subtype(
         ),
     )
     fd = IS.get_function_data(IS.get_value_curve(curve))
-    if !iszero(first(IS.get_x_coords(fd)))
+    if !iszero(first(IS.get_domain(fd)))
         throw(
             ArgumentError(
                 "For ImportExportCost, the first breakpoint must be zero.",
diff --git a/src/static_injector_models/thermal_generation.jl b/src/static_injector_models/thermal_generation.jl
index 14f549b..f1494c6 100644
--- a/src/static_injector_models/thermal_generation.jl
+++ b/src/static_injector_models/thermal_generation.jl
@@ -192,7 +192,7 @@ end
 function _onvar_cost(container::OptimizationContainer, cost_function::Union{PSY.FuelCurve{PSY.LinearCurve}, PSY.FuelCurve{PSY.QuadraticCurve}}, d::T, t::Int) where {T <: PSY.ThermalGen}
     value_curve = PSY.get_value_curve(cost_function)
     cost_component = PSY.get_function_data(value_curve)
-    # In Unit/h
+    # Cost at zero output (y-intercept), in Unit/h.
     constant_term = PSY.get_constant_term(cost_component)
     fuel_cost = PSY.get_fuel_cost(cost_function)
     if typeof(fuel_cost) <: Float64