diff --git a/src/execute.cpp b/src/execute.cpp
index 174dadf..8f44793 100644
--- a/src/execute.cpp
+++ b/src/execute.cpp
@@ -4,7 +4,7 @@ using namespace std;
 #include "include/execute.h"
 
 
-EvalResult execute(vector<string> input, Memory memory, int initial_line, ExecArgs args) {
+EvalResult execute(vector<string> input, Memory& memory, int initial_line, ExecArgs args) {
     try {
         vector<Token> tokens = tokenize(input, initial_line);
 
diff --git a/src/include/execute.h b/src/include/execute.h
index d785fd7..4208c5b 100644
--- a/src/include/execute.h
+++ b/src/include/execute.h
@@ -16,6 +16,6 @@ typedef struct ExecArgs {
     bool dump_mem=false;
 } ExecArgs;
 
-EvalResult execute(vector<string> input, Memory memory, int initial_line=0, ExecArgs args={});
+EvalResult execute(vector<string> input, Memory& memory, int initial_line=0, ExecArgs args={});
 
 #endif
\ No newline at end of file