diff --git a/model/config.go b/model/config.go
index afaa4bd..b5f4181 100644
--- a/model/config.go
+++ b/model/config.go
@@ -11,13 +11,14 @@ type Config struct {
 	Pattern         string `json:"pattern"           toml:"pattern"`
 	Team            string `json:"team"              toml:"team"`
 	SelfApprovalOff bool   `json:"self_approval_off" toml:"self_approval_off"`
-	DoMerge         bool `json:"do_merge" toml:"do_merge"`
-	DoVersion       bool `json:"do_version" toml:"do_version"`
+	DoMerge         bool   `json:"do_merge" toml:"do_merge"`
+	DoVersion       bool   `json:"do_version" toml:"do_version"`
 	ApprovalAlg     string `json:"approval_algorithm" toml:"approval_algorithm"`
 	VersionAlg      string `json:"version_algorithm" toml:"version_algorithm"`
-	VersionFormat string `json:"version_format" toml:"version_format"`
+	VersionFormat   string `json:"version_format" toml:"version_format"`
+	DoComment       bool   `json:"do_comment" toml:"do_comment"`
 
-	re              *regexp.Regexp
+	re *regexp.Regexp
 }
 
 // ParseConfig parses a projects .lgtm file
@@ -36,7 +37,7 @@ func ParseConfigStr(data string) (*Config, error) {
 		c.Approvals = 2
 	}
 	if len(c.Pattern) == 0 {
-		c.Pattern = `(?i)LGTM\s*(\S*)`
+		c.Pattern = `(?i)^LGTM\s*(\S*)`
 	}
 	if len(c.Team) == 0 {
 		c.Team = "MAINTAINERS"
diff --git a/model/status_hook.go b/model/status_hook.go
index 731da59..9a2e571 100644
--- a/model/status_hook.go
+++ b/model/status_hook.go
@@ -18,6 +18,7 @@ type Branch struct {
 
 type PRHook struct {
 	Number int
+	Update bool
 	Repo    *Repo
 }
 
diff --git a/remote/github/github.go b/remote/github/github.go
index 4930e18..47bccae 100644
--- a/remote/github/github.go
+++ b/remote/github/github.go
@@ -429,6 +429,7 @@ func (g *Github) GetPRHook(r *http.Request) (*model.PRHook, error) {
 	hook := new(model.PRHook)
 
 	hook.Number = data.Number
+	hook.Update = (data.Action == "synchronize")
 	hook.Repo = new(model.Repo)
 	hook.Repo.Owner = data.Repository.Owner.Login
 	hook.Repo.Name = data.Repository.Name
@@ -649,3 +650,16 @@ func (g *Github) Tag(u *model.User, r *model.Repo, version *string, sha *string)
 
 	return err
 }
+
+
+func (g *Github) WriteComment(u *model.User, r *model.Repo, num int, message string) error {
+	client := setupClient(g.API, u.Token)
+	emsg := "Message from LGTM -- " + message
+	_, _, err := client.Issues.CreateComment(r.Owner, r.Name, num, &github.IssueComment{
+		Body: github.String(emsg),
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/remote/remote.go b/remote/remote.go
index cbb7662..d564ef2 100644
--- a/remote/remote.go
+++ b/remote/remote.go
@@ -79,6 +79,9 @@ type Remote interface {
 
 	// UpdatePRsForCommit sets the commit's status to pending for LGTM if it is already on an open Pull Request
 	UpdatePRsForCommit(u *model.User, r *model.Repo, sha *string) (bool, error)
+
+	// WriteComment puts a new comment from LGTM into the PR
+	WriteComment(u *model.User, r *model.Repo, num int, message string) error
 }
 
 // GetUser authenticates a user with the remote system.
@@ -191,4 +194,8 @@ func GetPullRequestsForCommit(c context.Context, u *model.User, r *model.Repo, s
 
 func UpdatePRsForCommit(c context.Context, u *model.User, r *model.Repo, sha *string) (bool, error) {
 	return FromContext(c).UpdatePRsForCommit(u, r, sha)
+}
+
+func WriteComment(c context.Context, u *model.User, r *model.Repo, num int, message string) error {
+	return FromContext(c).WriteComment(u, r, num, message)
 }
\ No newline at end of file
diff --git a/web/hook.go b/web/hook.go
index cbf2a6f..be54ca5 100644
--- a/web/hook.go
+++ b/web/hook.go
@@ -52,6 +52,7 @@ func processPRHook(c *gin.Context, prHook *model.PRHook) {
 	if err != nil {
 		return
 	}
+
 	err = remote.SetStatus(c, user, repo, prHook.Number, false)
 	if err != nil {
 		log.Errorf("Error setting status. %s", err)
@@ -59,6 +60,20 @@ func processPRHook(c *gin.Context, prHook *model.PRHook) {
 		return
 	}
 
+	config, _, err := getConfigAndMaintainers(c, user, repo)
+	if err != nil {
+		return
+	}
+
+	if prHook.Update && config.DoComment {
+		err = remote.WriteComment(c, user, repo, prHook.Number, "The Pull Request has been updated. No comments before this one will count for approval.")
+		if err != nil {
+			log.Errorf("Error writing comment for status. %s", err)
+			c.String(500, "Error writing comment for status. %s", err)
+			return
+		}
+	}
+
 	c.IndentedJSON(200, gin.H{
 		"number":   prHook.Number,
 		"approved":    false,