diff --git a/src/misc1.c b/src/misc1.c
index 6bf7d75..3630d7b 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -5762,6 +5762,7 @@
 {
     char_u	*p;
     int		has_name = FALSE;
+    int		has_name_start = FALSE;
 
     s = cin_skipcomment(s);
     if (STRNCMP(s, "namespace", 9) == 0 && (s[9] == NUL || !vim_iswordc(s[9])))
@@ -5780,10 +5781,18 @@
 	    }
 	    else if (vim_iswordc(*p))
 	    {
+		has_name_start = TRUE;
 		if (has_name)
 		    return FALSE; /* word character after skipping past name */
 		++p;
 	    }
+	    else if (p[0] == ':' && p[1] == ':' && vim_iswordc(p[2]))
+	    {
+		if (!has_name_start || has_name)
+		    return FALSE;
+		/* C++ 17 nested namespace */
+		p += 3;
+	    }
 	    else
 	    {
 		return FALSE;
diff --git a/src/testdir/test3.in b/src/testdir/test3.in
index c0a68d0..096f152 100644
--- a/src/testdir/test3.in
+++ b/src/testdir/test3.in
Binary files differ
diff --git a/src/testdir/test3.ok b/src/testdir/test3.ok
index c4c01a3..2f9572c 100644
--- a/src/testdir/test3.ok
+++ b/src/testdir/test3.ok
@@ -1730,6 +1730,26 @@
 {
 111111111111111111;
 }
+namespace test::cpp17
+{
+111111111111111111;
+}
+namespace ::incorrectcpp17
+{
+	111111111111111111;
+}
+namespace test::incorrectcpp17::
+{
+	111111111111111111;
+}
+namespace test:incorrectcpp17
+{
+	111111111111111111;
+}
+namespace test:::incorrectcpp17
+{
+	111111111111111111;
+}
 namespace{
 111111111111111111;
 }
diff --git a/src/version.c b/src/version.c
index f07437d..5db35ab 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    92,
+/**/
     91,
 /**/
     90,