diff --git a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
index f752bce..a2323a9 100644
--- a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
+++ b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
@@ -8,10 +8,12 @@ import de.hsrm.compiler.Klang.nodes.loops.ForLoop;
 import de.hsrm.compiler.Klang.nodes.loops.WhileLoop;
 import de.hsrm.compiler.Klang.nodes.statements.*;
 import de.hsrm.compiler.Klang.types.Type;
+import org.antlr.v4.runtime.tree.TerminalNode;
 
 import java.util.*;
 
 public class ContextAnalysis extends KlangBaseVisitor<Node> {
+  Map<String, VariableDeclaration> params = new HashMap<>();
   Map<String, VariableDeclaration> vars = new HashMap<>();
   Map<String, FunctionDefinition> functionDefs;
   Map<String, StructDefinition> structDefs;
@@ -199,8 +201,8 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    if (vars.get(variableName) != null) {
-      var error = "Redeclaration of variable with name \"" + variableName + "\".";
+    if (vars.get(variableName) != null || params.get(variableName) != null) {
+      var error = "Redeclaration of variable or parameter with name \"" + variableName + "\".";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
@@ -236,31 +238,27 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitVariable_assignment(KlangParser.Variable_assignmentContext ctx) {
-    String name = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var name = ctx.IDENT().getText();
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
 
-    VariableDeclaration var = this.vars.get(name);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
+    var variableOrParameter = getVariableOrParameter(name, line, col);
 
     // Evaluate the expression
-    Expression expression = (Expression) this.visit(ctx.expression());
+    var expression = (Expression) visit(ctx.expression());
 
     // Make sure expression can be assigned to the variable
     try {
-      expression.type.combine(var.type);
+      expression.type.combine(variableOrParameter.type);
     } catch (Exception e) {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
     }
 
     // Since we assigned a value to this variable, we can consider it initialized
-    var.initialized = true;
+    variableOrParameter.initialized = true;
 
     // Create a new node and add the type of the expression to it
-    Node result = new VariableAssignment(name, expression);
+    var result = new VariableAssignment(name, expression);
     result.line = line;
     result.col = col;
     return result;
@@ -272,8 +270,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     ReturnStatement result = new ReturnStatement(expression);
 
     // Check if this expression is a tail recursion
-    if (expression instanceof FunctionCall) {
-      var funCall = (FunctionCall) expression;
+    if (expression instanceof FunctionCall funCall) {
       if (funCall.name.equals(this.currentFunctionDefinitionName)) {
         // Flag this function call
         funCall.isTailRecursive = true;
@@ -288,46 +285,24 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitField_assignment(KlangParser.Field_assignmentContext ctx) {
-    String varName = ctx.IDENT(0).getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
-    String[] path = new String[ctx.IDENT().size() - 1];
+    var varName = ctx.IDENT(0).getText();
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
+    var path = createStructPath(ctx.IDENT());
 
-    for (int i = 1; i < ctx.IDENT().size(); i++) {
-      path[i - 1] = ctx.IDENT(i).getText();
-    }
+    var variableOrParameter = getVariableOrParameter(varName, line, col);
+    ensureReferencesStruct(variableOrParameter, line, col);
+    var fieldType = drillType(variableOrParameter, path, line, col);
 
-    // Get the referenced variable, make sure it is defined
-    var variableDef = this.vars.get(varName);
-    if (variableDef == null) {
-      String error = "Variable with name " + varName + " not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Make sure it references a struct
-    if (variableDef.type.isPrimitiveType()) {
-      String error = "Variable must reference a struct but references " + variableDef.type.getName() + ".";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Get the type of the result of this expression
-    String structName = variableDef.type.getName();
-    Type fieldType;
-    try {
-      fieldType = Helper.drillType(this.structDefs, structName, path, 0);
-    } catch (Exception e) {
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
-    }
-
-    // Get the expression and make sure the type combines properly
-    Expression expression = (Expression) this.visit(ctx.expression());
+    // Visit the expression and make sure the type combines properly
+    var expression = (Expression) visit(ctx.expression());
     try {
       fieldType.combine(expression.type);
     } catch (Exception e) {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
     }
 
-    Node result = new FieldAssignment(varName, structName, path, expression);
+    var result = new FieldAssignment(varName, variableOrParameter.type.getName(), path, expression);
     result.col = col;
     result.line = line;
     return result;
@@ -338,23 +313,17 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     var baseName = ctx.IDENT(0).getText();
     var line = ctx.start.getLine();
     var col = ctx.start.getCharPositionInLine();
-
-    // Create a list of member names. This excludes
-    // the first entry as it is the base name.
-    var path = new ArrayList<String>();
-    for (int i = 1; i < ctx.IDENT().size(); i++) {
-      path.add(ctx.IDENT(i).getText());
-    }
+    var path = createStructPath(ctx.IDENT());
 
     // Determine if the base name points to an enum or a variable
     var enumDef = enumDefs.get(baseName);
     if (enumDef != null) {
-      if (path.size() != 1) {
+      if (path.length != 1) {
         var error = "Illegal access to enum " + enumDef.name + ".";
         throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
       }
 
-      var enumValueName = path.get(0);
+      var enumValueName = path[0];
       var enumValue = Arrays.stream(enumDef.enums)
               .filter(e -> e.value.equals(enumValueName))
               .findFirst()
@@ -371,29 +340,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       return enumAccessExpression;
     }
 
-    // Get the referenced variable, make sure it is defined
-    var variableDef = vars.get(baseName);
-    if (variableDef == null) {
-      var error = "Variable with name " + baseName + " not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
+    var variableOrParameter = getVariableOrParameter(baseName, line, col);
+    ensureReferencesStruct(variableOrParameter, line, col);
+    var resultType = drillType(variableOrParameter, path, line, col);
 
-    // Make sure it references a struct
-    if (variableDef.type.isPrimitiveType()) {
-      var error = "Variable must reference a struct but references " + variableDef.type.getName() + ".";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
-
-    // Get the type of the result of this expression
-    var structName = variableDef.type.getName();
-    Type resultType;
-    try {
-      resultType = Helper.drillType(structDefs, structName, path.toArray(new String[0]), 0);
-    } catch (Exception e) {
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
-    }
-
-    var memberAccessExpression = new MemberAccessExpression(baseName, structName, path.toArray(new String[0]));
+    var memberAccessExpression = new MemberAccessExpression(baseName, variableOrParameter.type.getName(), path);
     memberAccessExpression.type = resultType;
     memberAccessExpression.line = line;
     memberAccessExpression.col = col;
@@ -711,24 +662,20 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitVariable(KlangParser.VariableContext ctx) {
-    String name = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
+    var variableName = ctx.IDENT().getText();
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
 
-    VariableDeclaration var = this.vars.get(name);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
+    var variableOrParameter = getVariableOrParameter(variableName, line, col);
 
     // Make sure the variable has been initialized before it can be used
-    if (!var.initialized) {
-      String error = "Variable with name \"" + name + "\" has not been initialized.";
+    if (!variableOrParameter.initialized) {
+      var error = "Variable with name \"" + variableName + "\" has not been initialized.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    Variable result = new Variable(ctx.IDENT().getText());
-    result.type = var.type;
+    var result = new Variable(ctx.IDENT().getText());
+    result.type = variableOrParameter.type;
     result.line = line;
     result.col = col;
     return result;
@@ -839,23 +786,23 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    // Create a new set for the variables of the current function
+    // Create a new set for the variables and parameters of the current function
     // this will be filled in the variable declaration visitor as well
     vars = new HashMap<>();
+    params = new HashMap<>();
+
 
-    // Process the parameter list by visiting every parameter in it
     var paramCount = ctx.params.parameter().size();
-    var params = new Parameter[paramCount];
+    var functionParameters = new Parameter[paramCount]; // the list of parameters that get passed to FunctionDefinition
     for (int i = 0; i < paramCount; i++) {
-      // Add the parameter to the list of parameters
-      var param = (Parameter) visit(ctx.params.parameter(i));
-      params[i] = param;
+      functionParameters[i] = (Parameter) visit(ctx.params.parameter(i));
 
-      // add the param as a variable
-      var var = new VariableDeclaration(param.name);
-      var.initialized = true; // parameters can always be considered initialized
-      var.type = param.type;
-      vars.put(param.name, var);
+      // add the param as a variable to the global parameter map so that
+      // child nodes can access them.
+      var param = new VariableDeclaration(functionParameters[i].name);
+      param.initialized = true; // parameters can always be considered initialized
+      param.type = functionParameters[i].type;
+      params.put(param.name, param);
     }
 
     // Visit the block, make sure that a return value is guaranteed
@@ -867,7 +814,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    var functionDef = new FunctionDefinition(name, params, (Block) block);
+    var functionDef = new FunctionDefinition(name, functionParameters, vars.values().toArray(new VariableDeclaration[0]), (Block) block);
     functionDef.type = returnType;
     functionDef.line = ctx.start.getLine();
     functionDef.col = ctx.start.getCharPositionInLine();
@@ -988,19 +935,52 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitDestroy_statement(KlangParser.Destroy_statementContext ctx) {
-    String name = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
-    
-    VariableDeclaration var = this.vars.get(name);
-    if (var == null) {
-      String error = "Variable with name \"" + name + "\" not defined.";
-      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
-    }
+    var varName = ctx.IDENT().getText();
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
 
-    Node result = new DestructorCall(name);
+    var variableOrParameter = getVariableOrParameter(varName, line, col);
+    ensureReferencesStruct(variableOrParameter, line, col);
+
+    var result = new DestructorCall(varName);
     result.line = line;
     result.col = col;
     return result;
   }
+
+  private VariableDeclaration getVariableOrParameter(String name, int line, int col) {
+    var variable = vars.get(name);
+    var parameter = params.get(name);
+    if (variable == null && parameter == null) {
+      var error = "Variable or parameter with name \"" + name + "\" not defined.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+
+    return variable != null ? variable : parameter;
+  }
+
+  private void ensureReferencesStruct(VariableDeclaration variableOrParameter, int line, int col) {
+    if (variableOrParameter.type.isPrimitiveType() || enumDefs.containsKey(variableOrParameter.type.getName())) {
+      var error = "Variable or parameter must reference a struct but references " + variableOrParameter.type.getName() + ".";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+  }
+
+  private Type drillType(VariableDeclaration variableOrParameter, String[] path, int line, int col) {
+    try {
+      var structName = variableOrParameter.type.getName();
+      return Helper.drillType(structDefs, structName, path, 0);
+    } catch (Exception e) {
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + e.getMessage());
+    }
+  }
+
+  private String[] createStructPath(List<TerminalNode> identifiers) {
+    // Create a list of member names. This excludes the first entry as it is the base name.
+    var path = new String[identifiers.size() - 1];
+    for (int i = 1; i < identifiers.size(); i++) {
+      path[i - 1] = identifiers.get(i).getText();
+    }
+    return path;
+  }
 }
\ No newline at end of file
diff --git a/src/main/java/de/hsrm/compiler/Klang/GetDefinitions.java b/src/main/java/de/hsrm/compiler/Klang/GetDefinitions.java
index d5cf9e4..7445d23 100644
--- a/src/main/java/de/hsrm/compiler/Klang/GetDefinitions.java
+++ b/src/main/java/de/hsrm/compiler/Klang/GetDefinitions.java
@@ -210,7 +210,7 @@ public class GetDefinitions extends KlangBaseVisitor<Node> {
             parameters.put(paramName, parameter);
         }
 
-        var functionDef = new FunctionDefinition(funcName, parameters.values().toArray(new Parameter[0]), null);
+        var functionDef = new FunctionDefinition(funcName, parameters.values().toArray(new Parameter[0]), null, null);
         functionDef.type = Type.getByName(ctx.returnType.type().getText());
         functionDef.line = line;
         functionDef.col = col;
diff --git a/src/main/java/de/hsrm/compiler/Klang/nodes/FunctionDefinition.java b/src/main/java/de/hsrm/compiler/Klang/nodes/FunctionDefinition.java
index 45c1ca8..e008174 100644
--- a/src/main/java/de/hsrm/compiler/Klang/nodes/FunctionDefinition.java
+++ b/src/main/java/de/hsrm/compiler/Klang/nodes/FunctionDefinition.java
@@ -1,17 +1,20 @@
 package de.hsrm.compiler.Klang.nodes;
 
+import de.hsrm.compiler.Klang.nodes.statements.VariableDeclaration;
 import de.hsrm.compiler.Klang.visitors.Visitor;
 
 public class FunctionDefinition extends Node {
 
   public String name;
   public Parameter[] parameters;
+  public VariableDeclaration[] localVariables;
   public Block block;
 
-  public FunctionDefinition(String name, Parameter[] parameters, Block block) {
+  public FunctionDefinition(String name, Parameter[] parameters, VariableDeclaration[] localVariables, Block block) {
     this.name = name;
     this.parameters = parameters;
     this.block = block;
+    this.localVariables = localVariables;
   }
 
   @Override
diff --git a/src/main/java/de/hsrm/compiler/Klang/types/NamedType.java b/src/main/java/de/hsrm/compiler/Klang/types/NamedType.java
index 3dd028a..888be8f 100644
--- a/src/main/java/de/hsrm/compiler/Klang/types/NamedType.java
+++ b/src/main/java/de/hsrm/compiler/Klang/types/NamedType.java
@@ -1,11 +1,6 @@
 package de.hsrm.compiler.Klang.types;
 
 import de.hsrm.compiler.Klang.Value;
-import de.hsrm.compiler.Klang.nodes.EnumDefinition;
-import de.hsrm.compiler.Klang.nodes.FunctionDefinition;
-import de.hsrm.compiler.Klang.nodes.StructDefinition;
-
-import java.util.Map;
 
 public class NamedType extends Type {
     public String name;
@@ -49,8 +44,7 @@ public class NamedType extends Type {
             return true;
         }
 
-        if (that instanceof NamedType) {
-            var thatType = (NamedType) that;
+        if (that instanceof NamedType thatType) {
             return getName().equals(thatType.getName());
         }
 
diff --git a/src/test/java/DestroyStatementTest.java b/src/test/java/DestroyStatementTest.java
index 523c4b5..2051bcd 100644
--- a/src/test/java/DestroyStatementTest.java
+++ b/src/test/java/DestroyStatementTest.java
@@ -17,6 +17,6 @@ public class DestroyStatementTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:45 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:45 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 }
\ No newline at end of file
diff --git a/src/test/java/FieldAssignmentTest.java b/src/test/java/FieldAssignmentTest.java
index 32eeacb..651e290 100644
--- a/src/test/java/FieldAssignmentTest.java
+++ b/src/test/java/FieldAssignmentTest.java
@@ -17,7 +17,7 @@ public class FieldAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:46 Variable with name str not defined.", e.getMessage());
+        assertEquals("Error in line 1:46 Variable or parameter with name \"str\" not defined.", e.getMessage());
     }
 
     @Test
@@ -29,6 +29,6 @@ public class FieldAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:62 Variable must reference a struct but references int.", e.getMessage());
+        assertEquals("Error in line 1:62 Variable or parameter must reference a struct but references int.", e.getMessage());
     }
 }
\ No newline at end of file
diff --git a/src/test/java/FunctionDefinitionTest.java b/src/test/java/FunctionDefinitionTest.java
index b6086fc..a1ff3cf 100644
--- a/src/test/java/FunctionDefinitionTest.java
+++ b/src/test/java/FunctionDefinitionTest.java
@@ -92,4 +92,28 @@ public class FunctionDefinitionTest {
         var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
         assertEquals("Error in line 1:31 Parameter name Bar duplicates an enum of the same name.", e.getMessage());
     }
+
+    @Test
+    void shouldResetVariablesAndParameterEnvironment() {
+        // given
+        var tree = Helper.prepareParser("""
+                function foo(x: int): int {
+                  return 1;
+                }
+                function bar(): int {
+                  let x: int = 0;
+                  return x;
+                }
+                                
+                bar();
+                """);
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
 }
\ No newline at end of file
diff --git a/src/test/java/StructFieldAccessTest.java b/src/test/java/StructFieldAccessTest.java
index 9bda8f3..51c97c2 100644
--- a/src/test/java/StructFieldAccessTest.java
+++ b/src/test/java/StructFieldAccessTest.java
@@ -16,7 +16,7 @@ public class StructFieldAccessTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:53 Variable with name str not defined.", e.getMessage());
+        assertEquals("Error in line 1:53 Variable or parameter with name \"str\" not defined.", e.getMessage());
     }
 
     @Test
@@ -28,6 +28,6 @@ public class StructFieldAccessTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:69 Variable must reference a struct but references int.", e.getMessage());
+        assertEquals("Error in line 1:69 Variable or parameter must reference a struct but references int.", e.getMessage());
     }
 }
\ No newline at end of file
diff --git a/src/test/java/VariableAssignmentTest.java b/src/test/java/VariableAssignmentTest.java
index 292e5f4..1c08a33 100644
--- a/src/test/java/VariableAssignmentTest.java
+++ b/src/test/java/VariableAssignmentTest.java
@@ -17,6 +17,6 @@ public class VariableAssignmentTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:22 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:22 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 }
\ No newline at end of file
diff --git a/src/test/java/VariableTest.java b/src/test/java/VariableTest.java
index c9d2d39..8135774 100644
--- a/src/test/java/VariableTest.java
+++ b/src/test/java/VariableTest.java
@@ -17,7 +17,7 @@ public class VariableTest {
         ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
         
         Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:29 Variable with name \"x\" not defined.", e.getMessage());
+        assertEquals("Error in line 1:29 Variable or parameter with name \"x\" not defined.", e.getMessage());
     }
 
     @Test