diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 84bc97d40c..3ef88cabad 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -3233,7 +3233,13 @@ interval_mul(PG_FUNCTION_ARGS)
 	/* cascade units down */
 	result->day += (int32) month_remainder_days;
 	result_double = rint(span->time * factor + sec_remainder * USECS_PER_SEC);
-	if (result_double > PG_INT64_MAX || result_double < PG_INT64_MIN)
+	/*
+	* Since PG_INT64_MAX is not representable as a double-precision value, the
+	* cast result of (double) PG_INT64_MAX is 9223372036854775808. Therefore,
+	* we must use >= as a comparison operator when checking overflow.
+	*/
+	if (result_double >= (double) PG_INT64_MAX
+		|| result_double < (double) PG_INT64_MIN)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 				 errmsg("interval out of range")));
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index ed7652bfbf..1f1eac5449 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -1654,7 +1654,13 @@ coerceToInt(PgBenchValue *pval, int64 *ival)
 	{
 		double		dval = pval->u.dval;
 
-		if (dval < PG_INT64_MIN || PG_INT64_MAX < dval)
+		/*
+		 * Since PG_INT64_MAX is not representable as a double-precision value,
+		 * the cast result of (double) PG_INT64_MAX is 9223372036854775808.
+		 * Therefore, we must use <= as a comparison operator when checking
+		 * overflow.
+		 */
+		if (dval < (double) PG_INT64_MIN || (double) PG_INT64_MAX <= dval)
 		{
 			fprintf(stderr, "double to int overflow for %f\n", dval);
 			return false;