diff --git a/include/rtthread.h b/include/rtthread.h
index 92cdf012b24b2875fd7874d4449bb8eb44f8c842..70d4f38896ccd173efed2e69bbf5e24f0e2eb018 100644
--- a/include/rtthread.h
+++ b/include/rtthread.h
@@ -554,7 +554,7 @@ rt_int32_t rt_sscanf(const char *buf, const char *fmt, ...);
 char *rt_strncpy(char *dest, const char *src, rt_ubase_t n);
 void *rt_memmove(void *dest, const void *src, rt_ubase_t n);
 rt_int32_t rt_memcmp(const void *cs, const void *ct, rt_ubase_t count);
-rt_uint32_t rt_strcasecmp(const char *a, const char *b);
+rt_int32_t rt_strcasecmp(const char *a, const char *b);
 
 void rt_show_version(void);
 
diff --git a/src/kservice.c b/src/kservice.c
index 0a8786e17add34930b7fe772fa3723daa87068f8..1705ce5283bf6a3c5df1f9c252b22f1184b80335 100644
--- a/src/kservice.c
+++ b/src/kservice.c
@@ -370,7 +370,7 @@ RTM_EXPORT(rt_strstr);
  *
  * @return the result
  */
-rt_uint32_t rt_strcasecmp(const char *a, const char *b)
+rt_int32_t rt_strcasecmp(const char *a, const char *b)
 {
     int ca, cb;