2 files changed, 4 insertions, 3 deletions
diff --git a/chapter25/src/main/smp/sys/io.smp b/chapter25/src/main/smp/sys/io.smp
index 33fbdb5e..d6263ffe 100644
--- a/chapter25/src/main/smp/sys/io.smp
+++ b/chapter25/src/main/smp/sys/io.smp
@@ -12,7 +12,7 @@ val read = { i32 fd ->
     int len = 0;
     while( true ) {
         i32 rez = libc.read(fd,ptr,buf#);
-        if( rez > buf# ) libc._exit(libc.errno);
+        if( rez > buf# ) libc._exit(libc.errno());
         len += rez;
         if( rez < buf# )
             break;
diff --git a/chapter25/src/main/smp/sys/libc.smp b/chapter25/src/main/smp/sys/libc.smp
index 133b5bf7..17ee65cb 100644
--- a/chapter25/src/main/smp/sys/libc.smp
+++ b/chapter25/src/main/smp/sys/libc.smp
@@ -30,8 +30,9 @@ i32 STDERR = 2;
 
 // status
 {  i32 -> i32 } _exit = "C";
-// Error return from many native calls
-i32 errno = "C";
+// errno is not an ordinary C data symbol; read it through the native runtime.
+{ i32 } simple_errno = "C";
+val errno = { -> simple_errno(); };
 // addr len prot flags fd  off -> void*
 {  i64  i64 i32  i32   i32 i32 -> i64 } mmap = "C";
 // mmap flags