diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index bf61fd7dbc0..2a296909492 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -4430,35 +4430,62 @@ int8_numeric(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(int64_to_numeric(val));
 }
 
+int64
+numeric_int8_opt_error(Numeric num, bool *have_error)
+{
+	NumericVar	x;
+	int64		result;
+
+	if (have_error)
+		*have_error = false;
+
+	if (NUMERIC_IS_SPECIAL(num))
+	{
+		if (have_error)
+		{
+			*have_error = true;
+			return 0;
+		}
+		else
+		{
+			if (NUMERIC_IS_NAN(num))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("cannot convert NaN to %s", "bigint")));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("cannot convert infinity to %s", "bigint")));
+		}
+	}
+
+	/* Convert to variable format, then convert to int8 */
+	init_var_from_num(num, &x);
+
+	if (!numericvar_to_int64(&x, &result))
+	{
+		if (have_error)
+		{
+			*have_error = true;
+			return 0;
+		}
+		else
+		{
+			ereport(ERROR,
+					(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+					 errmsg("bigint out of range")));
+		}
+	}
+
+	return result;
+}
 
 Datum
 numeric_int8(PG_FUNCTION_ARGS)
 {
 	Numeric		num = PG_GETARG_NUMERIC(0);
-	NumericVar	x;
-	int64		result;
 
-	if (NUMERIC_IS_SPECIAL(num))
-	{
-		if (NUMERIC_IS_NAN(num))
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot convert NaN to %s", "bigint")));
-		else
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot convert infinity to %s", "bigint")));
-	}
-
-	/* Convert to variable format and thence to int8 */
-	init_var_from_num(num, &x);
-
-	if (!numericvar_to_int64(&x, &result))
-		ereport(ERROR,
-				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
-				 errmsg("bigint out of range")));
-
-	PG_RETURN_INT64(result);
+	PG_RETURN_INT64(numeric_int8_opt_error(num, NULL));
 }
 
 
diff --git a/src/include/utils/numeric.h b/src/include/utils/numeric.h
index 08e4f8c217d..0780b52094d 100644
--- a/src/include/utils/numeric.h
+++ b/src/include/utils/numeric.h
@@ -101,5 +101,6 @@ extern Numeric numeric_div_opt_error(Numeric num1, Numeric num2,
 extern Numeric numeric_mod_opt_error(Numeric num1, Numeric num2,
 									 bool *have_error);
 extern int32 numeric_int4_opt_error(Numeric num, bool *have_error);
+extern int64 numeric_int8_opt_error(Numeric num, bool *have_error);
 
 #endif							/* _PG_NUMERIC_H_ */