diff -u a/dios/libc/_PDCLIB/glue.c b/dios/libc/_PDCLIB/glue.c
--- a/dios/libc/_PDCLIB/glue.c	2020-03-06 10:37:02.556345366 +0100
+++ b/dios/libc/_PDCLIB/glue.c	2020-03-06 10:37:02.559678687 +0100
@@ -101,8 +101,10 @@
         void *mem = __vm_obj_make( n * size, _VM_PT_Heap ); // success
         memset( mem, 0, n * size );
         r = mem;
-    } else
+    } else {
+        errno = ENOMEM;
         r = NULL; // failure
+    }
     __dios_mask( masked );
     return r;
 }