diff --git a/datafusion/sql/src/unparser/plan.rs b/datafusion/sql/src/unparser/plan.rs
index ee111be19d1e..97c15c633b9a 100644
--- a/datafusion/sql/src/unparser/plan.rs
+++ b/datafusion/sql/src/unparser/plan.rs
@@ -866,7 +866,7 @@ impl Unparser<'_> {
             JoinType::LeftSemi => ast::JoinOperator::LeftSemi(constraint),
             JoinType::RightAnti => ast::JoinOperator::RightAnti(constraint),
             JoinType::RightSemi => ast::JoinOperator::RightSemi(constraint),
-            JoinType::LeftMark | JoinType::RightMark => unimplemented!("Unparsing of Left Mark join type"),
+            JoinType::LeftMark | JoinType::RightMark => unimplemented!("Unparsing of mark join type"),
         })
     }