diff --git a/src/interpreter.cpp b/src/interpreter.cpp
index d41ff18..7b246a5 100644
--- a/src/interpreter.cpp
+++ b/src/interpreter.cpp
@@ -82,6 +82,20 @@ EvalResult eval(Node &ast) {
                 
                 return expr;
             } break;
+            case NodeType::LIncr:
+            case NodeType::RIncr: {
+                Token identifierTok = get<Token>(node.children[0]);
+                string identifier = get<string>(identifierTok.data);
+
+                return node.type == NodeType::LIncr ? ++memory[identifier] : memory[identifier]++;
+            }
+            case NodeType::LDecr:
+            case NodeType::RDecr: {
+                Token identifierTok = get<Token>(node.children[0]);
+                string identifier = get<string>(identifierTok.data);
+
+                return node.type == NodeType::LDecr ? --memory[identifier] : memory[identifier]--;
+            }
         }
     }
     else {