diff --git a/libsrc/rp6502/close.c b/libsrc/rp6502/close.c
index dd7e38115..9dea5bdc3 100644
--- a/libsrc/rp6502/close.c
+++ b/libsrc/rp6502/close.c
@@ -1,5 +1,5 @@
 #include <rp6502.h>
-#include <errno.h>
+#include <fcntl.h>
 
 int __fastcall__ close (int fd)
 {
diff --git a/libsrc/rp6502/open.c b/libsrc/rp6502/open.c
index ab3a374a2..2061c9813 100644
--- a/libsrc/rp6502/open.c
+++ b/libsrc/rp6502/open.c
@@ -1,12 +1,14 @@
 #include <rp6502.h>
 #include <errno.h>
 #include <string.h>
+#include <fcntl.h>
 
 int __cdecl__ open (const char* name, int flags, ...)
 {
     size_t namelen = strlen (name);
     if (namelen > 255) {
-        return _mappederrno (EINVAL);
+        RIA.errno = EINVAL;
+        return _mappederrno(RIA.errno);
     }
     while (namelen) {
         ria_push_char (name[--namelen]);
diff --git a/libsrc/rp6502/stdin_opt.c b/libsrc/rp6502/stdin_opt.c
index 3a9ccfde4..69e6f51cd 100644
--- a/libsrc/rp6502/stdin_opt.c
+++ b/libsrc/rp6502/stdin_opt.c
@@ -1,4 +1,3 @@
-
 #include <rp6502.h>
 
 int __fastcall__ stdin_opt (unsigned long ctrl_bits, unsigned char str_length)
diff --git a/libsrc/rp6502/sysremove.c b/libsrc/rp6502/sysremove.c
index d8c1ced98..22d2a65fc 100644
--- a/libsrc/rp6502/sysremove.c
+++ b/libsrc/rp6502/sysremove.c
@@ -7,7 +7,8 @@ unsigned char __fastcall__ _sysremove (const char* name)
     size_t namelen;
     namelen = strlen (name);
     if (namelen > 255) {
-        return _mappederrno (EINVAL);
+        RIA.errno = EINVAL;
+        return __mappederrno(RIA.errno);
     }
     while (namelen) {
         ria_push_char (name[--namelen]);
diff --git a/libsrc/rp6502/sysrename.c b/libsrc/rp6502/sysrename.c
index 46bdd8b31..e05ad725a 100644
--- a/libsrc/rp6502/sysrename.c
+++ b/libsrc/rp6502/sysrename.c
@@ -8,7 +8,8 @@ unsigned char __fastcall__ _sysrename (const char* oldpath, const char* newpath)
     oldpathlen = strlen (oldpath);
     newpathlen = strlen (newpath);
     if (oldpathlen + newpathlen > 510) {
-        return _mappederrno (EINVAL);
+        RIA.errno = EINVAL;
+        return __mappederrno(RIA.errno);
     }
     while (oldpathlen) {
         ria_push_char (oldpath[--oldpathlen]);
diff --git a/libsrc/rp6502/write_xstack.c b/libsrc/rp6502/write_xstack.c
index 29285a87e..b356ec706 100644
--- a/libsrc/rp6502/write_xstack.c
+++ b/libsrc/rp6502/write_xstack.c
@@ -5,7 +5,8 @@ int __fastcall__ write_xstack (const void* buf, unsigned count, int fildes)
 {
     unsigned i;
     if (count > 512) {
-        return _mappederrno (EINVAL);
+        RIA.errno = EINVAL;
+        return __mappederrno(RIA.errno);
     }
     for (i = count; i;) {
         ria_push_char (((char*)buf)[--i]);