diff --git a/include/string.h b/include/string.h
index 3a86e9eb24..7ddfb0df05 100644
--- a/include/string.h
+++ b/include/string.h
@@ -110,4 +110,24 @@ static inline int strcmp(const char *s1, const char *s2)
 	return c1 - c2;
 }
 
+/**
+ * Compare two strings with fixed length.
+ *
+ * @param s1 The first string.
+ * @param s2 The second string.
+ * @param maxlen Return at most maxlen characters as length of the string.
+ * @return A non-zero value if s1 and s2 differ, or zero if s1 equals s2.
+ */
+static inline int strncmp(const char *s1, const char *s2, int maxlen)
+{
+	int i;
+
+	for (i = 0; i < maxlen; i++) {
+		if (s1[i] != s2[i])
+			return s1[i] - s2[i];
+	}
+
+	return 0;
+}
+
 #endif				/* STRING_H */
diff --git a/lib/lar.c b/lib/lar.c
index fd079619b5..da0ec44eb6 100644
--- a/lib/lar.c
+++ b/lib/lar.c
@@ -92,7 +92,7 @@ int find_file(struct mem_file *archive, const char *filename, struct mem_file *r
 	for (walk = archive->start;
 	     (walk < (char *)(archive->start + archive->len - sizeof(struct lar_header))) && 
 			(walk >= (char *)archive->start); walk += 16) {
-		if (strcmp(walk, MAGIC) != 0)
+		if (strncmp(walk, MAGIC, 8) != 0)
 			continue;
 
 		header = (struct lar_header *)walk;