diff --git a/builtin/providers/aws/validators.go b/builtin/providers/aws/validators.go
index 526505bc9..c802376db 100644
--- a/builtin/providers/aws/validators.go
+++ b/builtin/providers/aws/validators.go
@@ -641,9 +641,10 @@ func validateSecurityRuleType(v interface{}, k string) (ws []string, errors []er
 func validateOnceAWeekWindowFormat(v interface{}, k string) (ws []string, errors []error) {
 	// valid time format is "ddd:hh24:mi"
 	validTimeFormat := "(sun|mon|tue|wed|thu|fri|sat):([0-1][0-9]|2[0-3]):([0-5][0-9])"
+	validTimeFormatConsolidated := "^(" + validTimeFormat + "-" + validTimeFormat + "|)$"
 
 	value := strings.ToLower(v.(string))
-	if !regexp.MustCompile(validTimeFormat + "-" + validTimeFormat).MatchString(value) {
+	if !regexp.MustCompile(validTimeFormatConsolidated).MatchString(value) {
 		errors = append(errors, fmt.Errorf(
 			"%q must satisfy the format of \"ddd:hh24:mi-ddd:hh24:mi\".", k))
 	}
@@ -653,9 +654,10 @@ func validateOnceAWeekWindowFormat(v interface{}, k string) (ws []string, errors
 func validateOnceADayWindowFormat(v interface{}, k string) (ws []string, errors []error) {
 	// valid time format is "hh24:mi"
 	validTimeFormat := "([0-1][0-9]|2[0-3]):([0-5][0-9])"
+	validTimeFormatConsolidated := "^(" + validTimeFormat + "-" + validTimeFormat + "|)$"
 
 	value := v.(string)
-	if !regexp.MustCompile(validTimeFormat + "-" + validTimeFormat).MatchString(value) {
+	if !regexp.MustCompile(validTimeFormatConsolidated).MatchString(value) {
 		errors = append(errors, fmt.Errorf(
 			"%q must satisfy the format of \"hh24:mi-hh24:mi\".", k))
 	}
diff --git a/builtin/providers/aws/validators_test.go b/builtin/providers/aws/validators_test.go
index a49bfeeab..8920ae764 100644
--- a/builtin/providers/aws/validators_test.go
+++ b/builtin/providers/aws/validators_test.go
@@ -1006,6 +1006,11 @@ func TestValidateOnceAWeekWindowFormat(t *testing.T) {
 			Value:    "Sun:04:00-Sun:05:00",
 			ErrCount: 0,
 		},
+		{
+			// valid format
+			Value:    "",
+			ErrCount: 0,
+		},
 	}
 
 	for _, tc := range cases {
@@ -1042,6 +1047,11 @@ func TestValidateOnceADayWindowFormat(t *testing.T) {
 			Value:    "04:00-05:00",
 			ErrCount: 0,
 		},
+		{
+			// valid format
+			Value:    "",
+			ErrCount: 0,
+		},
 	}
 
 	for _, tc := range cases {