diff --git a/dbms/src/Interpreters/ProjectionManipulation.h b/dbms/src/Interpreters/ProjectionManipulation.h
index 1d1ea0996ef..6bc4815b547 100644
--- a/dbms/src/Interpreters/ProjectionManipulation.h
+++ b/dbms/src/Interpreters/ProjectionManipulation.h
@@ -7,7 +7,7 @@ namespace DB {
 
 class ExpressionAnalyzer;
 
-class ScopeStack;
+struct ScopeStack;
 
 namespace ErrorCodes {
 extern const int CONDITIONAL_TREE_PARENT_NOT_FOUND;