diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index d5159ab..5ca5380 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -1158,7 +1158,9 @@
 # CFLAGS with /Fo$(OUTDIR)/
 CFLAGS_OUTDIR=$(CFLAGS) /Fo$(OUTDIR)/
 
-conflags = /nologo /subsystem:$(SUBSYSTEM)
+# Add /opt:ref to remove unreferenced functions and data even when /DEBUG is
+# added.
+conflags = /nologo /subsystem:$(SUBSYSTEM) /opt:ref
 
 PATHDEF_SRC = $(OUTDIR)\pathdef.c
 
diff --git a/src/version.c b/src/version.c
index 2cc9977..14bf136 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1646,
+/**/
     1645,
 /**/
     1644,