diff --git a/Makefile b/Makefile
index 385679a..4103a6b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 SOURCE:= src/*.c
 TEST_SOURCE:= src/test/*.c
 INCLUDE:= include/
-CFLAGS:= -Wall -g --std=gnu99
+CFLAGS:= -Wall -g --std=c11
 OBJ:= obj
 BUILD:= build
 LFLAGS:= -L./$(BUILD) -lse
diff --git a/include/libse.h b/include/libse.h
index b9460dd..49299e8 100644
--- a/include/libse.h
+++ b/include/libse.h
@@ -13,6 +13,8 @@ typedef struct {
 typedef struct cons {
 	union {
 		void* ptr;
+		struct cons* car_l;
+		char* car_s;
 		car_t car;
 	};
 	struct cons* cdr;
@@ -41,5 +43,8 @@ enum _se_type se_typeof(list_t* cons); //Get type of cons's car value.
 list_t* se_new(char* from, int dupe); //Create new cons.
 #define se_newd(f) se_new((f), 1)
 list_t* se_last(list_t* list); //Get last non-nil cons.
+car_t se_make(const char* fmt); //Parse "input" as string and "(input)" as sexpr and return as car_t. (NULL returns NIL).
+void se_rplaca(list_t* cons, car_t car); //Replace car of cons with `car'
+void se_rplacd(list_t* cons, list_t* cdr); //Replace cdr of cons with 'cdr'
 
 #endif /* _LIBSE_H */
diff --git a/src/libse.c b/src/libse.c
index 0c9eb35..ff900bc 100644
--- a/src/libse.c
+++ b/src/libse.c
@@ -5,6 +5,15 @@
 #include <libse.h>
 #include <internal/exstring.h>
 
+static char* strdup(const char* str)
+{
+	register size_t size = strlen(str);
+	char* ret = malloc(size+1);
+	memcpy(ret, str, size);
+	ret[size] = 0;
+	return ret;
+}
+
 static void _addcar(list_t* out, exString* token, int nil, int ucase)
 {
 	if(ucase)
@@ -304,3 +313,60 @@ list_t* se_new(char* str, int dupe)
 {
 	return _se_new(str, SE_STRING, dupe); //We don't need the list part.
 }
+
+car_t se_make(const char* fmt)
+{
+	if(!fmt) 
+	{
+		car_t c;
+		memset(&c, 0, sizeof(car_t));
+		return c;
+	}
+
+	while(*fmt && iws(*fmt))
+	{
+		fmt+=1;
+	}
+	if(!*fmt) return se_make(NULL);
+	else if(*fmt == '(') {
+		car_t c;
+		list_t* ret =  se_parse(fmt, SETP_DEFAULT);
+		memset(&c,0,sizeof(car_t));
+		c.ptr = ret;
+		c.alloced= 1;
+		c.size = sizeof(list_t);
+		c.sexpr = 1;
+		return c;
+	}
+	else {
+		car_t c;
+		memset(&c,0,sizeof(car_t));
+		c.ptr = strdup(fmt);
+		c.alloced=1;
+		c.size = strlen((char*)c.ptr);
+		return c;
+	}
+}
+
+void se_rplaca(list_t* cons, car_t car)
+{
+	if(cons->car.alloced && cons->ptr)
+	{
+		switch(se_typeof(cons))
+		{
+			case SE_LIST:
+				se_free(cons->ptr); break;
+			case SE_STRING:
+				free(cons->ptr); break;
+			default: break;
+		}
+	}
+	memcpy(&cons->car, &car, sizeof(car_t));
+}
+
+void se_rplacd(list_t* cons, list_t* cdr)
+{
+	if(cons->cdr)
+		se_free(cons->cdr);
+	cons->cdr = cdr;
+}
diff --git a/src/test/main.c b/src/test/main.c
index 9b4de4d..a1e8ee8 100644
--- a/src/test/main.c
+++ b/src/test/main.c
@@ -25,12 +25,12 @@ void test_exs()
 	
 	exs_nappendc(test, 'A', 6);
 
-	exs_appendf(test, "\nCurrent size: %d -> %d", strlen(EXS(test)), exs_realsize(test));
+	exs_appendf(test, "\nCurrent size: %ld -> %ld", strlen(EXS(test)), exs_realsize(test));
 	exs_appendf(test, "AOISDJOAIJS%s", "sokdok");
 
 	printf("%s\n", EXS(test));
 
-	printf("strlen() %d, ->currentSize %d\n", strlen(EXS(test)), exs_realsize(test)); 
+	printf("strlen() %ld, ->currentSize %ld\n", strlen(EXS(test)), exs_realsize(test)); 
 
 	exs_free(test);
 }
@@ -59,6 +59,10 @@ void test_parse()
 		return;
 	}
 	//printf("Parse okay.\n");
+	
+	se_rplaca(list, se_make("test1"));
+	se_rplaca(list->cdr, se_make("(test)"));
+	se_rplacd(list->cdr->car_l, se_make("(list)").ptr);
 
 	se_print(NULL, list);
 	printf("\n");