diff --git a/libtcc.c b/libtcc.c
index db30223..6aa2afd 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -132,7 +132,7 @@ BOOL WINAPI DllMain (HINSTANCE hDll, DWORD dwReason, LPVOID lpReserved)
 
 /********************************************************/
 /* copy a string and truncate it. */
-ST_FUNC char *pstrcpy(char *buf, int buf_size, const char *s)
+ST_FUNC char *pstrcpy(char *buf, size_t buf_size, const char *s)
 {
     char *q, *q_end;
     int c;
@@ -152,9 +152,9 @@ ST_FUNC char *pstrcpy(char *buf, int buf_size, const char *s)
 }
 
 /* strcat and truncate. */
-ST_FUNC char *pstrcat(char *buf, int buf_size, const char *s)
+ST_FUNC char *pstrcat(char *buf, size_t buf_size, const char *s)
 {
-    int len;
+    size_t len;
     len = strlen(buf);
     if (len < buf_size)
         pstrcpy(buf + len, buf_size - len, s);
diff --git a/tcc.h b/tcc.h
index 6c70f33..59061bc 100644
--- a/tcc.h
+++ b/tcc.h
@@ -1120,8 +1120,8 @@ ST_DATA int tcc_ext;
 ST_DATA struct TCCState *tcc_state;
 
 /* public functions currently used by the tcc main function */
-ST_FUNC char *pstrcpy(char *buf, int buf_size, const char *s);
-ST_FUNC char *pstrcat(char *buf, int buf_size, const char *s);
+ST_FUNC char *pstrcpy(char *buf, size_t buf_size, const char *s);
+ST_FUNC char *pstrcat(char *buf, size_t buf_size, const char *s);
 ST_FUNC char *pstrncpy(char *out, const char *in, size_t num);
 PUB_FUNC char *tcc_basename(const char *name);
 PUB_FUNC char *tcc_fileextension (const char *name);