diff --git a/google-beta/resource_compute_resource_policy.go b/google-beta/resource_compute_resource_policy.go
index ef17caad1f..b8120727fe 100644
--- a/google-beta/resource_compute_resource_policy.go
+++ b/google-beta/resource_compute_resource_policy.go
@@ -92,9 +92,10 @@ which cannot be a dash.`,
 													Description: `The number of days between snapshots.`,
 												},
 												"start_time": {
-													Type:     schema.TypeString,
-													Required: true,
-													ForceNew: true,
+													Type:         schema.TypeString,
+													Required:     true,
+													ForceNew:     true,
+													ValidateFunc: validateHourlyOnly,
 													Description: `This must be in UTC format that resolves to one of
 00:00, 04:00, 08:00, 12:00, 16:00, or 20:00. For example,
 both 13:00-5 and 08:00 are valid.`,
@@ -118,12 +119,14 @@ both 13:00-5 and 08:00 are valid.`,
 													Description: `The number of hours between snapshots.`,
 												},
 												"start_time": {
-													Type:     schema.TypeString,
-													Required: true,
-													ForceNew: true,
+													Type:         schema.TypeString,
+													Required:     true,
+													ForceNew:     true,
+													ValidateFunc: validateHourlyOnly,
 													Description: `Time within the window to start the operations.
-It must be in format "HH:MM",
-where HH : [00-23] and MM : [00-00] GMT.`,
+It must be in an hourly format "HH:MM",
+where HH : [00-23] and MM : [00] GMT.
+eg: 21:00`,
 												},
 											},
 										},
diff --git a/google-beta/validation.go b/google-beta/validation.go
index 3a59f006b4..7ce1ccd209 100644
--- a/google-beta/validation.go
+++ b/google-beta/validation.go
@@ -261,3 +261,23 @@ func StringNotInSlice(invalid []string, ignoreCase bool) schema.SchemaValidateFu
 		return
 	}
 }
+
+// Ensure that hourly timestamp strings "HH:MM" have the minutes zeroed out for hourly only inputs
+func validateHourlyOnly(val interface{}, key string) (warns []string, errs []error) {
+	v := val.(string)
+	parts := strings.Split(v, ":")
+	if len(parts) != 2 {
+		errs = append(errs, fmt.Errorf("%q must be in the format HH:00, got: %s", key, v))
+		return
+	}
+	if parts[1] != "00" {
+		errs = append(errs, fmt.Errorf("%q does not allow minutes, it must be in the format HH:00, got: %s", key, v))
+	}
+	i, err := strconv.Atoi(parts[0])
+	if err != nil {
+		errs = append(errs, fmt.Errorf("%q cannot be parsed, it must be in the format HH:00, got: %s", key, v))
+	} else if i < 0 || i > 23 {
+		errs = append(errs, fmt.Errorf("%q does not specify a valid hour, it must be in the format HH:00 where HH : [00-23], got: %s", key, v))
+	}
+	return
+}
diff --git a/website/docs/r/compute_resource_policy.html.markdown b/website/docs/r/compute_resource_policy.html.markdown
index b704b5c8cd..2ea2df6fe1 100644
--- a/website/docs/r/compute_resource_policy.html.markdown
+++ b/website/docs/r/compute_resource_policy.html.markdown
@@ -152,8 +152,9 @@ The `hourly_schedule` block supports:
 * `start_time` -
   (Required)
   Time within the window to start the operations.
-  It must be in format "HH:MM",
-  where HH : [00-23] and MM : [00-00] GMT.
+  It must be in an hourly format "HH:MM",
+  where HH : [00-23] and MM : [00] GMT.
+  eg: 21:00
 
 The `daily_schedule` block supports: