diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 99fffc9e1bfd6ebf4959ac6415d8e80e19deff56..677139b48e000d0d98100122c851eff5572aa14a 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -283,9 +283,9 @@ unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
 
 /*****************************************************************************/
 /*
- * set up a mapping
+ * set up a mapping for shared memory segments
  */
 int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
 {
-	return 0;
+	return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;
 }