--- old/src/hotspot/share/oops/instanceKlass.cpp	2020-04-13 21:03:46.000000000 -0700
+++ new/src/hotspot/share/oops/instanceKlass.cpp	2020-04-13 21:03:46.000000000 -0700
@@ -2682,13 +2682,20 @@
     dest[dest_index++] = src[src_index++];
   }
 
-  if (is_hidden()) { // Replace the last '+' with a '.'.
-    for (int index = (int)src_length; index > 0; index--) {
+  if (is_hidden()) {
+    int end_class = -1;
+    for (int index = (int)dest_index-1; index > 0; index--) {  // dest[0] is "L"
+      dest[index+1] = dest[index];
       if (dest[index] == '+') {
-        dest[index] = JVM_SIGNATURE_DOT;
+        // Replace the last '+' with a ';' followed with '/'.
+        dest[index] = JVM_SIGNATURE_ENDCLASS;
+        dest[index+1] = JVM_SIGNATURE_SLASH;
+        end_class = index;
         break;
       }
     }
+    assert(end_class > 0, "unexpected hidden class name");
+    dest_index++;
   }
 
   // If we have a hash, append it
@@ -2697,7 +2704,9 @@
   }
 
   // Add the semicolon and the NULL
-  dest[dest_index++] = JVM_SIGNATURE_ENDCLASS;
+  if (!is_hidden()) {
+    dest[dest_index++] = JVM_SIGNATURE_ENDCLASS;
+  }
   dest[dest_index] = '\0';
   return dest;
 }