diff --git a/donate.html b/donate.html
index 7030caa..9dc933c 100644
--- a/donate.html
+++ b/donate.html
@@ -44,6 +44,7 @@ DO NOT CHANGE THIS FILE.
             </p>
             <p>
                 <ul type="none">
+                    <li>Ken Seergobin</li>
                     <li>Francesco De Simone</li>
                     <li>Nicola Giacobbe</li>
                     <li>Devulder Jean-Paul</li>
diff --git a/output/my_basic.exe b/output/my_basic.exe
index 2857147..8b272f8 100755
Binary files a/output/my_basic.exe and b/output/my_basic.exe differ
diff --git a/output/my_basic_mac b/output/my_basic_mac
index ff08a11..817cea6 100755
Binary files a/output/my_basic_mac and b/output/my_basic_mac differ
diff --git a/sample/yard/level.bas b/sample/yard/level.bas
index f5cb8e9..e83e5ff 100644
--- a/sample/yard/level.bas
+++ b/sample/yard/level.bas
@@ -88,7 +88,7 @@ class level
 		c.name = "Therapist"
 		c.talk_handler = lambda (_)
 		(
-			print "- " + _.name + ": give you 23 HP";
+			print "- " + _.name + ": gives you 23 HP";
 			_.alive = false
 			role.hp = role.hp + 23
 		)
diff --git a/sample/yard/utils.bas b/sample/yard/utils.bas
index 4d83c49..e408f7c 100644
--- a/sample/yard/utils.bas
+++ b/sample/yard/utils.bas
@@ -4,7 +4,7 @@
 ' For more information about MY-BASIC, see https://github.com/paladin-t/my_basic/
 
 def cls()
-	if os() = "WIN" then
+	if os() = "WINDOWS" then
 		sys("cls")
 	else
 		sys("clear")
diff --git a/shell/main.c b/shell/main.c
index 56d13d9..d4bf933 100755
--- a/shell/main.c
+++ b/shell/main.c
@@ -441,6 +441,7 @@ static void _destroy_code(void) {
 		free(code->lines[i]);
 	free(code->lines);
 	free(code);
+	code = 0;
 }
 
 static void _clear_code(void) {
@@ -582,16 +583,15 @@ static void _destroy_importing_directories(void) {
 		free(importing_dirs->dirs[i]);
 	free(importing_dirs->dirs);
 	free(importing_dirs);
+	importing_dirs = 0;
 }
 
-static _importing_dirs_t* _set_importing_directories(char* dirs) {
+static _importing_dirs_t* _set_importing_directories(const char* dirs) {
 	_importing_dirs_t* result = 0;
-	char* end = 0;
 
 	if(!dirs)
 		return result;
 
-	end = dirs + strlen(dirs);
 	result = (_importing_dirs_t*)malloc(sizeof(_importing_dirs_t));
 	_CHECK_MEM(result);
 	result->count = 0;
@@ -599,23 +599,26 @@ static _importing_dirs_t* _set_importing_directories(char* dirs) {
 	result->dirs = (char**)malloc(sizeof(char*) * result->size);
 	_CHECK_MEM(result->dirs);
 
-	while(dirs && dirs < end && *dirs) {
+	while(dirs && *dirs) {
 		int l = 0;
 		char* buf = 0;
 		bool_t as = false;
-		strtok(dirs, ";");
-		if(!(*dirs))
-			continue;
-		if(*dirs == ';') { dirs++; continue; }
+		const char* p = dirs;
+		dirs = strchr(dirs, ';');
+		if(dirs) {
+			l = dirs - p;
+			if(*dirs == ';') ++dirs;
+		} else {
+			l = strlen(p);
+		}
 		if(result->count + 1 == result->size) {
 			result->size += _REALLOC_INC_STEP;
 			result->dirs = (char**)realloc(result->dirs, sizeof(char*) * result->size);
 		}
-		l = (int)strlen(dirs);
-		as = dirs[l - 1] != '/' && dirs[l - 1] != '\\';
+		as = p[l - 1] != '/' && p[l - 1] != '\\';
 		buf = (char*)malloc(l + (as ? 2 : 1));
 		_CHECK_MEM(buf);
-		memcpy(buf, dirs, l);
+		memcpy(buf, p, l);
 		if(as) {
 			buf[l] = '/';
 			buf[l + 1] = '\0';
@@ -627,7 +630,6 @@ static _importing_dirs_t* _set_importing_directories(char* dirs) {
 			if(*buf == '\\') *buf = '/';
 			buf++;
 		}
-		dirs += l + 1;
 	}
 
 	_destroy_importing_directories();