diff --git a/src/compiler/codegen/events.ts b/src/compiler/codegen/events.ts
index 5ee53e54b17..69947d64cde 100644
--- a/src/compiler/codegen/events.ts
+++ b/src/compiler/codegen/events.ts
@@ -114,12 +114,13 @@ function genHandler(
         }
       } else if (key === 'exact') {
         const modifiers = handler.modifiers
-        genModifierCode += genGuard(
-          ['ctrl', 'shift', 'alt', 'meta']
-            .filter(keyModifier => !modifiers[keyModifier])
-            .map(keyModifier => `$event.${keyModifier}Key`)
-            .join('||')
-        )
+        const exactModifiers = ['ctrl', 'shift', 'alt', 'meta']
+          .filter(keyModifier => !modifiers[keyModifier])
+          .map(keyModifier => `$event.${keyModifier}Key`)
+          .join('||')
+        if (exactModifiers) {
+          genModifierCode += genGuard(exactModifiers)
+        }
       } else {
         keys.push(key)
       }
diff --git a/test/unit/modules/compiler/codegen.spec.ts b/test/unit/modules/compiler/codegen.spec.ts
index aab2505f254..bd8e019f45f 100644
--- a/test/unit/modules/compiler/codegen.spec.ts
+++ b/test/unit/modules/compiler/codegen.spec.ts
@@ -455,6 +455,11 @@ describe('codegen', () => {
       '<input @click.ctrl.exact="onClick">',
       `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;if($event.shiftKey||$event.altKey||$event.metaKey)return null;return onClick.apply(null, arguments)}}})}`
     )
+    // #12319: all system modifiers with .exact should not generate syntax error
+    assertCodegen(
+      '<input @keydown.ctrl.shift.alt.meta.exact="onKeydown">',
+      `with(this){return _c('input',{on:{"keydown":function($event){if(!$event.ctrlKey)return null;if(!$event.shiftKey)return null;if(!$event.altKey)return null;if(!$event.metaKey)return null;return onKeydown.apply(null, arguments)}}})}`
+    )
   })
 
   it('generate events with multiple modifiers', () => {