diff --git a/decompiler/structures/pseudo/operations.py b/decompiler/structures/pseudo/operations.py
index 1b8c88d89..95045067c 100644
--- a/decompiler/structures/pseudo/operations.py
+++ b/decompiler/structures/pseudo/operations.py
@@ -10,7 +10,7 @@
 
 from decompiler.util.insertion_ordered_set import InsertionOrderedSet
 
-from .expressions import Constant, Expression, FunctionSymbol, ImportedFunctionSymbol, IntrinsicSymbol, Symbol, Tag, Variable
+from .expressions import Constant, Expression, IntrinsicSymbol, Symbol, Tag, Variable
 from .typing import CustomType, Pointer, Type, UnknownType
 
 T = TypeVar("T")
@@ -470,7 +470,7 @@ class Call(Operation):
 
     def __init__(
         self,
-        function: Union[FunctionSymbol, ImportedFunctionSymbol, IntrinsicSymbol, Variable],
+        function: Expression,
         parameter: List[Expression],
         vartype: Type = UnknownType(),
         writes_memory: Optional[int] = None,
@@ -522,7 +522,7 @@ def requirements_iter(self) -> Iterator[Variable]:
         yield from super().requirements_iter
 
     @property
-    def function(self) -> Union[FunctionSymbol, ImportedFunctionSymbol, IntrinsicSymbol, Variable]:
+    def function(self) -> Expression:
         """Return the name of the function called."""
         return self._function
 
diff --git a/decompiler/structures/visitors/substitute_visitor.py b/decompiler/structures/visitors/substitute_visitor.py
index 4e3928dc4..1cd71fec5 100644
--- a/decompiler/structures/visitors/substitute_visitor.py
+++ b/decompiler/structures/visitors/substitute_visitor.py
@@ -11,10 +11,7 @@
     Continue,
     DataflowObject,
     Expression,
-    FunctionSymbol,
     GenericBranch,
-    ImportedFunctionSymbol,
-    IntrinsicSymbol,
     ListOperation,
     MemPhi,
     Operation,
@@ -152,7 +149,7 @@ def visit_binary_operation(self, op: BinaryOperation) -> Optional[DataflowObject
 
     def visit_call(self, op: Call) -> Optional[DataflowObject]:
         if (function_replacement := op.function.accept(self)) is not None:
-            op._function = _assert_type(function_replacement, Union[FunctionSymbol, ImportedFunctionSymbol, IntrinsicSymbol, Variable])
+            op._function = _assert_type(function_replacement, Expression)
 
         return self._visit_operation(op)