diff --git a/browser/components/urlbar/private/SuggestBackendRust.sys.mjs b/browser/components/urlbar/private/SuggestBackendRust.sys.mjs
index c5120937cf43..ca6dfa1febe1 100644
--- a/browser/components/urlbar/private/SuggestBackendRust.sys.mjs
+++ b/browser/components/urlbar/private/SuggestBackendRust.sys.mjs
@@ -1005,14 +1005,6 @@ return
 ]
 ;
 }
-searchString
-=
-searchString
-.
-toLocaleLowerCase
-(
-)
-;
 /
 /
 Build
diff --git a/browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_yelp.js b/browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_yelp.js
index be3932d16602..89e01fb64cac 100644
--- a/browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_yelp.js
+++ b/browser/components/urlbar/tests/quicksuggest/browser/browser_quicksuggest_yelp.js
@@ -247,11 +247,11 @@ search
 ?
 find_desc
 =
-ramen
+RaMeN
 &
 find_loc
 =
-tokyo
+tOkYo
 "
 )
 ;
@@ -265,9 +265,9 @@ payload
 .
 title
 "
-ramen
-in
-tokyo
+RaMeN
+iN
+tOkYo
 "
 )
 ;
diff --git a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_addons.js b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_addons.js
index dc4cfbc7fe3e..9cbe032cdf9d 100644
--- a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_addons.js
+++ b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_addons.js
@@ -1899,6 +1899,41 @@ false
 }
 )
 }
+{
+input
+:
+"
+FoUrTh
+"
+expected
+:
+makeExpectedResult
+(
+{
+suggestion
+:
+REMOTE_SETTINGS_RESULTS
+[
+0
+]
+.
+attachment
+[
+3
+]
+source
+:
+"
+remote
+-
+settings
+"
+setUtmParams
+:
+false
+}
+)
+}
 ]
 ;
 UrlbarPrefs
diff --git a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_dynamicWikipedia.js b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_dynamicWikipedia.js
index 6980467a520c..833416e87704 100644
--- a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_dynamicWikipedia.js
+++ b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_dynamicWikipedia.js
@@ -255,6 +255,51 @@ sponsored
 }
 )
 ;
+add_task
+(
+async
+function
+mixedCaseQuery
+(
+)
+{
+await
+check_results
+(
+{
+context
+:
+createContext
+(
+"
+TeSt
+"
+{
+providers
+:
+[
+UrlbarProviderQuickSuggest
+.
+name
+]
+isPrivate
+:
+false
+}
+)
+matches
+:
+[
+makeExpectedResult
+(
+)
+]
+}
+)
+;
+}
+)
+;
 function
 makeExpectedResult
 (
diff --git a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_mdn.js b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_mdn.js
index 9391a3ebfbd5..579274514144 100644
--- a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_mdn.js
+++ b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_mdn.js
@@ -925,6 +925,75 @@ forceSync
 }
 )
 ;
+add_task
+(
+async
+function
+mixedCaseQuery
+(
+)
+{
+const
+suggestion
+=
+REMOTE_SETTINGS_DATA
+[
+0
+]
+.
+attachment
+[
+1
+]
+;
+const
+keyword
+=
+"
+InPuT
+"
+;
+await
+check_results
+(
+{
+context
+:
+createContext
+(
+keyword
+{
+providers
+:
+[
+UrlbarProviderQuickSuggest
+.
+name
+]
+isPrivate
+:
+false
+}
+)
+matches
+:
+[
+makeExpectedResult
+(
+{
+searchString
+:
+keyword
+suggestion
+}
+)
+]
+}
+)
+;
+}
+)
+;
 function
 makeExpectedResult
 (
diff --git a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_yelp.js b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_yelp.js
index 7634cd370985..ba1d28bc5210 100644
--- a/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_yelp.js
+++ b/browser/components/urlbar/tests/quicksuggest/unit/test_quicksuggest_yelp.js
@@ -240,24 +240,24 @@ search
 ?
 find_desc
 =
-best
+BeSt
 +
-ramen
+RaMeN
 +
-delivery
+dElIvErY
 &
 find_loc
 =
-tokyo
+tOkYo
 "
 title
 :
 "
-best
-ramen
-delivery
-in
-tokyo
+BeSt
+RaMeN
+dElIvErY
+iN
+tOkYo
 "
 }
 }