diff --git a/src/expression/CMakeLists.txt b/src/expression/CMakeLists.txt
index 99a818db..0241ec67 100644
--- a/src/expression/CMakeLists.txt
+++ b/src/expression/CMakeLists.txt
@@ -5,6 +5,7 @@ set(SELF_SRCS
     GeneralizedExpression.cpp
     Expression.cpp
     DefineExpr.cpp
+    AssignExpr.cpp
     Apply.cpp
     Lambda.cpp
     Variable.cpp