diff --git a/custom/conf/app.example.ini b/custom/conf/app.example.ini
index 476b305026..8362f22812 100644
--- a/custom/conf/app.example.ini
+++ b/custom/conf/app.example.ini
@@ -938,7 +938,7 @@ PATH =
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
-;; List of prefixes used in Pull Request title to mark them as Work In Progress
+;; List of prefixes used in Pull Request title to mark them as Work In Progress (matched in a case-insensitive manner)
 ;WORK_IN_PROGRESS_PREFIXES = WIP:,[WIP]
 ;;
 ;; List of keywords used in Pull Request comments to automatically close a related issue
diff --git a/docs/content/doc/advanced/config-cheat-sheet.en-us.md b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
index 4c43ba7ddb..785fd3d6c2 100644
--- a/docs/content/doc/advanced/config-cheat-sheet.en-us.md
+++ b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
@@ -87,7 +87,7 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 ### Repository - Pull Request (`repository.pull-request`)
 
 - `WORK_IN_PROGRESS_PREFIXES`: **WIP:,\[WIP\]**: List of prefixes used in Pull Request
- title to mark them as Work In Progress
+ title to mark them as Work In Progress. These are matched in a case-insensitive manner.
 - `CLOSE_KEYWORDS`: **close**, **closes**, **closed**, **fix**, **fixes**, **fixed**, **resolve**, **resolves**, **resolved**: List of
  keywords used in Pull Request comments to automatically close a related issue
 - `REOPEN_KEYWORDS`: **reopen**, **reopens**, **reopened**: List of keywords used in Pull Request comments to automatically reopen
diff --git a/models/pull.go b/models/pull.go
index bb5bb11812..df96e2dc74 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -588,7 +588,7 @@ func (pr *PullRequest) IsWorkInProgress() bool {
 // HasWorkInProgressPrefix determines if the given PR title has a Work In Progress prefix
 func HasWorkInProgressPrefix(title string) bool {
 	for _, prefix := range setting.Repository.PullRequest.WorkInProgressPrefixes {
-		if strings.HasPrefix(strings.ToUpper(title), prefix) {
+		if strings.HasPrefix(strings.ToUpper(title), strings.ToUpper(prefix)) {
 			return true
 		}
 	}
@@ -609,7 +609,7 @@ func (pr *PullRequest) GetWorkInProgressPrefix() string {
 	}
 
 	for _, prefix := range setting.Repository.PullRequest.WorkInProgressPrefixes {
-		if strings.HasPrefix(strings.ToUpper(pr.Issue.Title), prefix) {
+		if strings.HasPrefix(strings.ToUpper(pr.Issue.Title), strings.ToUpper(prefix)) {
 			return pr.Issue.Title[0:len(prefix)]
 		}
 	}