diff --git a/src/map.c b/src/map.c
index ea7567e..186550a 100644
--- a/src/map.c
+++ b/src/map.c
@@ -726,6 +726,8 @@
 				    mpp = &(mp->m_next);
 				    continue;
 				}
+				// In keyround for simplified keys, don't unmap
+				// a mapping without m_simplified flag.
 				if (keyround1_simplified && !mp->m_simplified)
 				    break;
 				// We reset the indicated mode bits. If nothing
diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index e0008d6..b413f4f 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -1627,7 +1627,7 @@
   set mouse&
 endfunc
 
-func Test_unmap_simplfied()
+func Test_unmap_simplifiable()
   map <C-I> foo
   map <Tab> bar
   call assert_equal('foo', maparg('<C-I>'))
@@ -1636,6 +1636,11 @@
   call assert_equal('', maparg('<C-I>'))
   call assert_equal('bar', maparg('<Tab>'))
   unmap <Tab>
+
+  map <C-I> foo
+  unmap <Tab>
+  " This should not error
+  unmap <C-I>
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 2998d2d..945b6a1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4828,
+/**/
     4827,
 /**/
     4826,