diff --git a/src/Interpreters/Squashing.cpp b/src/Interpreters/Squashing.cpp
index 3872c2ba6b9..82d80114a85 100644
--- a/src/Interpreters/Squashing.cpp
+++ b/src/Interpreters/Squashing.cpp
@@ -8,7 +8,6 @@ namespace DB
 {
 namespace ErrorCodes
 {
-    extern const int SIZES_OF_COLUMNS_DOESNT_MATCH;
     extern const int LOGICAL_ERROR;
 }