diff --git a/std/regex/internal/parser.d b/std/regex/internal/parser.d
index 6498bddb74a..0a1ecdec04b 100644
--- a/std/regex/internal/parser.d
+++ b/std/regex/internal/parser.d
@@ -1182,6 +1182,8 @@ if (isForwardRange!R && is(ElementType!R : dchar))
                     state = State.Start;
                     break;
                 default:
+                    if (current >= privateUseStart && current <= privateUseEnd)
+                       enforce(false, "no matching ']' found while parsing character class");
                     enforce(false, "invalid escape sequence");
                 }
                 break;
@@ -1256,8 +1258,17 @@ if (isForwardRange!R && is(ElementType!R : dchar))
                     end = parseUniHex(pat, 8);
                     break;
                 default:
+                    if (current >= privateUseStart && current <= privateUseEnd)
+                       enforce(false, "no matching ']' found while parsing character class");
                     error("invalid escape sequence");
                 }
+                // Lookahead to check if it's a \T
+                // where T is sub-pattern terminator in multi-pattern scheme
+                if (end == '\\' && !pat.empty)
+                {
+                    if (pat.front >= privateUseStart && pat.front <= privateUseEnd)
+                        enforce(false, "invalid escape sequence");
+                }
                 enforce(last <= end,"inverted range");
                 set.add(last, end + 1);
                 state = State.Start;
@@ -1364,8 +1375,7 @@ if (isForwardRange!R && is(ElementType!R : dchar))
                     "character class syntax error");
                 enforce(!opstack.empty, "unmatched ']'");
                 opstack.pop();
-                next();
-                if (opstack.empty)
+                if (!next() || opstack.empty)
                     break L_CharsetLoop;
                 auto pair  = parseCharTerm();
                 if (!pair[0].empty)//not only operator e.g. -- or ~~
@@ -1390,10 +1400,13 @@ if (isForwardRange!R && is(ElementType!R : dchar))
                 }
                 vstack.push(pair[0]);
             }
-
         }while (!empty || !opstack.empty);
         while (!opstack.empty)
-            apply(opstack.pop(),vstack);
+        {
+            enforce(opstack.top != Operator.Open,
+                "no matching ']' found while parsing character class");
+            apply(opstack.pop(), vstack);
+        }
         assert(vstack.length == 1);
         g.charsetToIr(vstack.top);
     }
@@ -1483,6 +1496,13 @@ if (isForwardRange!R && is(ElementType!R : dchar))
             g.markBackref(nref);
             break;
         default:
+            // Lookahead to check if it's a \T
+            // where T is sub-pattern terminator in multi-pattern scheme
+            if (current == '\\' && !pat.empty)
+            {
+                if (pat.front >= privateUseStart && current <= privateUseEnd)
+                    enforce(false, "invalid escape sequence");
+            }
             if (current >= privateUseStart && current <= privateUseEnd)
             {
                 g.endPattern(current - privateUseStart + 1);
diff --git a/std/regex/internal/tests.d b/std/regex/internal/tests.d
index 80e278bf648..5415f45b4c3 100644
--- a/std/regex/internal/tests.d
+++ b/std/regex/internal/tests.d
@@ -1082,3 +1082,19 @@ alias Sequence(int B, int E) = staticIota!(B, E);
     assert(equal!equal(s.matchAll(ctr), outcomes));
     assert(equal!equal(s.bmatch(r), outcomes));
 }
+
+// bugzilla 17667
+@safe unittest
+{
+    import std.algorithm.searching : canFind;
+    void willThrow(T)(T arg, string msg)
+    {
+        auto e = collectException(regex(arg));
+        assert(e.msg.canFind(msg), e.msg);
+    }
+    willThrow([r".", r"[\(\{[\]\}\)]"], "no matching ']' found while parsing character class");
+    willThrow([r"[\", r"123"], "no matching ']' found while parsing character class");
+    willThrow([r"[a-", r"123"], "no matching ']' found while parsing character class");
+    willThrow([r"[a-\", r"123"], "invalid escape sequence");
+    willThrow([r"\", r"123"], "invalid escape sequence");
+}