diff --git a/libbb/libbb.h b/libbb/libbb.h
index 102596c..3b0ced7 100644
--- a/libbb/libbb.h
+++ b/libbb/libbb.h
@@ -243,7 +243,11 @@
 extern struct hostent *xgethostbyname(const char *name);
 
 char *dirname (const char *path);
-char *strdup_substr (const char *s, int start, int end);
+
+static inline char *strdup_substr (const char *s, int start, int end)
+{
+        return xstrndup (s+start, end-start);
+}
 int make_directory (char *path, mode_t mode, int flags);
 
 #define CT_AUTO	0