diff --git a/lldb/include/lldb/Expression/ExpressionVariable.h b/lldb/include/lldb/Expression/ExpressionVariable.h
--- a/lldb/include/lldb/Expression/ExpressionVariable.h
+++ b/lldb/include/lldb/Expression/ExpressionVariable.h
@@ -207,6 +207,8 @@
   /// LLVM RTTI support
   static char ID;
 
+  PersistentExpressionState();
+
   virtual ~PersistentExpressionState();
 
   virtual lldb::ExpressionVariableSP
diff --git a/lldb/source/Expression/ExpressionVariable.cpp b/lldb/source/Expression/ExpressionVariable.cpp
--- a/lldb/source/Expression/ExpressionVariable.cpp
+++ b/lldb/source/Expression/ExpressionVariable.cpp
@@ -34,6 +34,8 @@
 
 char PersistentExpressionState::ID;
 
+PersistentExpressionState::PersistentExpressionState() = default;
+
 PersistentExpressionState::~PersistentExpressionState() = default;
 
 lldb::addr_t PersistentExpressionState::LookupSymbol(ConstString name) {