diff --git a/AppKit/fifo.c b/AppKit/fifo.c
index a24e210..47b721b 100644
--- a/AppKit/fifo.c
+++ b/AppKit/fifo.c
@@ -35,8 +35,7 @@ os_err_t fifo_get(fifo_t* self, uint8_t* data){
         *data = self->buffer[read_idx];
     }
 
-    os_size_t next_read_idx = fifo_next(self, self->read_idx);
-    self->read_idx = next_read_idx;
+    self->read_idx = fifo_next(self, self->read_idx);
     return OS_ERR_OK;
 }
 
diff --git a/AppKit/str_util.c b/AppKit/str_util.c
new file mode 100644
index 0000000..f51a433
--- /dev/null
+++ b/AppKit/str_util.c
@@ -0,0 +1,33 @@
+#include <str_util.h>
+
+
+const char* str_util_strnstr(const char* haystack, const char* needle, os_size_t needle_len) {
+    if (needle_len == 0) return (char*)haystack;
+    if (!haystack || !needle || haystack[0]=='\0') return NULL;
+
+    os_size_t haystack_len = strlen(haystack);
+    if (haystack_len < needle_len) return NULL;
+
+    for (os_size_t i = 0; i <= haystack_len - needle_len; i++) {
+        if (memcmp(haystack + i, needle, needle_len) == 0) {
+            return haystack + i;
+        }
+    }
+    return NULL;
+}
+
+const char* str_util_strstr(const char* haystack, const char* needle) {
+    if (!haystack || !needle || haystack[0]=='\0' || needle[0]=='\0') return NULL;
+
+    os_size_t needle_len = strlen(needle);
+    os_size_t haystack_len = strlen(haystack);
+    if (haystack_len < needle_len) return NULL;
+
+    for (os_size_t i = 0; i <= haystack_len - needle_len; i++) {
+        if (memcmp(haystack + i, needle, needle_len) == 0) {
+            return haystack + i;
+        }
+    }
+    return NULL;
+}
+
diff --git a/AppKit/str_util.h b/AppKit/str_util.h
new file mode 100644
index 0000000..3a3fb81
--- /dev/null
+++ b/AppKit/str_util.h
@@ -0,0 +1,28 @@
+#ifndef INCLUDED_STR_UTIL_H
+#define INCLUDED_STR_UTIL_H
+
+#ifndef INCLUDED_OS_TYPES_H
+#include <os_types.h>
+#endif /*INCLUDED_OS_TYPES_H*/
+
+/* ------------------------------------------------------------------------------------------------------------------ */
+/*  */
+
+/**
+ *
+ * @param haystack
+ * @param needle
+ * @return
+ */
+const char* str_util_strstr(const char* haystack, const char* needle);
+
+/**
+ *
+ * @param haystack
+ * @param needle
+ * @param needle_len
+ * @return
+ */
+const char* str_util_strnstr(const char* haystack, const char* needle, os_size_t needle_len);
+
+#endif /*INCLUDED_STR_UTIL_H*/