diff --git a/src/charset.c b/src/charset.c
index cdb9e48..d649179 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1733,6 +1733,8 @@
 	if (enc_latin1like)
 	    return latin1upper[c];
     }
+    if (c < 0x80 && (cmp_flags & CMP_KEEPASCII))
+	return TOUPPER_ASC(c);
     return TOUPPER_LOC(c);
 }
 
@@ -1757,6 +1759,8 @@
 	if (enc_latin1like)
 	    return latin1lower[c];
     }
+    if (c < 0x80 && (cmp_flags & CMP_KEEPASCII))
+	return TOLOWER_ASC(c);
     return TOLOWER_LOC(c);
 }
 #endif
diff --git a/src/testdir/test_normal.vim b/src/testdir/test_normal.vim
index aa82992..155ddbf 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -1619,6 +1619,17 @@
       call assert_equal("i\u0131", getline(1))
       call assert_equal("i\u0131", tolower("iI"))
 
+      set casemap&
+      call setline(1, 'iI')
+      1normal gUU
+      call assert_equal("II", getline(1))
+      call assert_equal("II", toupper("iI"))
+
+      call setline(1, 'iI')
+      1normal guu
+      call assert_equal("ii", getline(1))
+      call assert_equal("ii", tolower("iI"))
+
       lang en_US.UTF-8
     catch /E197:/
       " can't use Turkish locale
diff --git a/src/version.c b/src/version.c
index 9fb32c9..578cfe3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    554,
+/**/
     553,
 /**/
     552,