diff --git a/include/linux/string.h b/include/linux/string.h
index dee2214..c61306d 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -13,11 +13,6 @@
 extern "C" {
 #endif
 
-extern char * strpbrk(const char *,const char *);
-extern char * strsep(char **,const char *);
-extern __kernel_size_t strspn(const char *,const char *);
-extern __kernel_size_t strcspn(const char *,const char *);
-
 extern char *strndup_user(const char __user *, long);
 
 /*
@@ -70,6 +65,18 @@
 #ifndef __HAVE_ARCH_STRNLEN
 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
 #endif
+#ifndef __HAVE_ARCH_STRPBRK
+extern char * strpbrk(const char *,const char *);
+#endif
+#ifndef __HAVE_ARCH_STRSEP
+extern char * strsep(char **,const char *);
+#endif
+#ifndef __HAVE_ARCH_STRSPN
+extern __kernel_size_t strspn(const char *,const char *);
+#endif
+#ifndef __HAVE_ARCH_STRCSPN
+extern __kernel_size_t strcspn(const char *,const char *);
+#endif
 
 #ifndef __HAVE_ARCH_MEMSET
 extern void * memset(void *,int,__kernel_size_t);
diff --git a/lib/string.c b/lib/string.c
index 037a48a..7be6f0a 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -362,6 +362,7 @@
 EXPORT_SYMBOL(strspn);
 #endif
 
+#ifndef __HAVE_ARCH_STRCSPN
 /**
  * strcspn - Calculate the length of the initial substring of @s which does
  * 	not contain letters in @reject
@@ -384,6 +385,7 @@
 	return count;
 }
 EXPORT_SYMBOL(strcspn);
+#endif
 
 #ifndef __HAVE_ARCH_STRPBRK
 /**