diff --git a/preprocessor/ExprNode.hh b/preprocessor/ExprNode.hh
index 048196cae..bef4a4157 100644
--- a/preprocessor/ExprNode.hh
+++ b/preprocessor/ExprNode.hh
@@ -34,7 +34,6 @@ using namespace std;
 class DataTree;
 class VariableNode;
 class BinaryOpNode;
-class SymbolTable;
 
 typedef class ExprNode *expr_t;
 
diff --git a/preprocessor/ExternalFunctionsTable.hh b/preprocessor/ExternalFunctionsTable.hh
index 0dfe698ac..b5218bea5 100644
--- a/preprocessor/ExternalFunctionsTable.hh
+++ b/preprocessor/ExternalFunctionsTable.hh
@@ -28,7 +28,6 @@ using namespace std;
 #include <map>
 
 #include "SymbolTable.hh"
-class SymbolTable;
 
 enum ExternalFunctionSetOrNot
   {