diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 0e1f2166847..8e932f0388d 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -4830,7 +4830,15 @@ numeric_combine(PG_FUNCTION_ARGS)
 	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
 
 	if (state2 == NULL)
+	{
+		/*
+		 * NULL state2 is easy, just return state1, which we know is already
+		 * in the agg_context
+		 */
+		if (state1 == NULL)
+			PG_RETURN_NULL();
 		PG_RETURN_POINTER(state1);
+	}
 
 	/* manually copy all fields from state2 to state1 */
 	if (state1 == NULL)
@@ -4922,7 +4930,15 @@ numeric_avg_combine(PG_FUNCTION_ARGS)
 	state2 = PG_ARGISNULL(1) ? NULL : (NumericAggState *) PG_GETARG_POINTER(1);
 
 	if (state2 == NULL)
+	{
+		/*
+		 * NULL state2 is easy, just return state1, which we know is already
+		 * in the agg_context
+		 */
+		if (state1 == NULL)
+			PG_RETURN_NULL();
 		PG_RETURN_POINTER(state1);
+	}
 
 	/* manually copy all fields from state2 to state1 */
 	if (state1 == NULL)
@@ -5445,7 +5461,15 @@ numeric_poly_combine(PG_FUNCTION_ARGS)
 	state2 = PG_ARGISNULL(1) ? NULL : (PolyNumAggState *) PG_GETARG_POINTER(1);
 
 	if (state2 == NULL)
+	{
+		/*
+		 * NULL state2 is easy, just return state1, which we know is already
+		 * in the agg_context
+		 */
+		if (state1 == NULL)
+			PG_RETURN_NULL();
 		PG_RETURN_POINTER(state1);
+	}
 
 	/* manually copy all fields from state2 to state1 */
 	if (state1 == NULL)
@@ -5672,7 +5696,15 @@ int8_avg_combine(PG_FUNCTION_ARGS)
 	state2 = PG_ARGISNULL(1) ? NULL : (PolyNumAggState *) PG_GETARG_POINTER(1);
 
 	if (state2 == NULL)
+	{
+		/*
+		 * NULL state2 is easy, just return state1, which we know is already
+		 * in the agg_context
+		 */
+		if (state1 == NULL)
+			PG_RETURN_NULL();
 		PG_RETURN_POINTER(state1);
+	}
 
 	/* manually copy all fields from state2 to state1 */
 	if (state1 == NULL)