diff --git a/src/exec.c b/src/exec.c
index bb62d6f..ae2b956 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -21,23 +21,23 @@ ASTNumData exec_call(AST* ast) {
     log_dbg("Started call execution.");
     fflush(stdout);
     ASTCallData* calldata = (ASTCallData*)ast->data;
-    if (!strcmp(calldata->to, "+") && calldata->argc == 2) {
+    if (!strcmp(calldata->to, "sum") && calldata->argc == 2) {
 
         ASTNumData n1 = exec_expr(calldata->argv[0]);
         ASTNumData n2 = exec_expr(calldata->argv[1]);
 
         return n1 + n2;
-    } else if (!strcmp(calldata->to, "-") && calldata->argc == 2) {
+    } else if (!strcmp(calldata->to, "sub") && calldata->argc == 2) {
         ASTNumData n1 = exec_expr(calldata->argv[0]);
         ASTNumData n2 = exec_expr(calldata->argv[1]);
 
         return n1 - n2;
-    } else if (!strcmp(calldata->to, "*") && calldata->argc == 2) {
+    } else if (!strcmp(calldata->to, "mul") && calldata->argc == 2) {
         ASTNumData n1 = exec_expr(calldata->argv[0]);
         ASTNumData n2 = exec_expr(calldata->argv[1]);
 
         return n1 * n2;
-    } else if (!strcmp(calldata->to, "/") && calldata->argc == 2) {
+    } else if (!strcmp(calldata->to, "div") && calldata->argc == 2) {
         ASTNumData n1 = exec_expr(calldata->argv[0]);
         ASTNumData n2 = exec_expr(calldata->argv[1]);
 
diff --git a/src/grammar.y b/src/grammar.y
index 870af2f..a6d7d32 100644
--- a/src/grammar.y
+++ b/src/grammar.y
@@ -46,74 +46,74 @@ exp:
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("+", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("sum", 2, argv));
     }
     | NEG NUM PLUS NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("+", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("sum", 2, argv));
     }
     | NUM NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("-", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("sub", 2, argv));
     }
     | NEG NUM NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("-", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("sub", 2, argv));
     }
 
     | NUM MULT NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("mul", 2, argv));
     }
     | NEG NUM MULT NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("mul", 2, argv));
     }
     | NEG NUM MULT NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$5));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("mul", 2, argv));
     }
     | NUM MULT NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("mul", 2, argv));
     }
 
     | NUM DIV NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("/", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("div", 2, argv));
     }
     | NEG NUM DIV NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("/", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("div", 2, argv));
     }
     | NEG NUM DIV NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$5));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("/", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("div", 2, argv));
     }
     | NUM DIV NEG NUM {
         AST** argv = calloc(2, sizeof(AST*));
         argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
         argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("/", 2, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("div", 2, argv));
     }
 %%