diff --git a/Makefile b/Makefile
index 150b04a..f2d0f83 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
 CC = gcc
-CPPFLAGS = -Isrc/ -D_POSIX_C_SOURCE=200809L
+CPPFLAGS = -Isrc/ -D_POSIX_C_SOURCE=200809L -D_USE_CLIMBING=$(USE_CLIMBING)
 CFLAGS = -Wall -Wextra -pedantic -Werror -std=c99
 VPATH = src/
+USE_CLIMBING = 1
 
 SRC = \
     src/ast/ast.c \
diff --git a/src/evalexpr.c b/src/evalexpr.c
index 50c431b..67432d5 100644
--- a/src/evalexpr.c
+++ b/src/evalexpr.c
@@ -5,6 +5,10 @@
 #include "eval/eval.h"
 #include "parse/parse.h"
 
+#ifndef _USE_CLIMBING
+# define _USE_CLIMBING 0
+#endif
+
 int main(void)
 {
     char *line = NULL;
@@ -13,7 +17,11 @@ int main(void)
 
     while ((getline(&line, &size, stdin)) > 0)
     {
+#if _USE_CLIMBING
+        struct ast_node *ast = climbing_parse(line);
+#else
         struct ast_node *ast = recursive_parse(line);
+#endif
 
         if (ast == NULL)
         {