diff --git a/autoload/vimspector.vim b/autoload/vimspector.vim
index 7cecca5..168a239 100644
--- a/autoload/vimspector.vim
+++ b/autoload/vimspector.vim
@@ -235,7 +235,9 @@ function! vimspector#AddWatch( ... ) abort
     return
   endif
   if a:0 == 0
-    let expr = input( 'Enter watch expression: ' )
+    let expr = input( 'Enter watch expression: ',
+                    \ '',
+                    \ 'custom,vimspector#CompleteExpr' )
   else
     let expr = a:1
   endif
diff --git a/python3/vimspector/utils.py b/python3/vimspector/utils.py
index 10da7e1..e7cb537 100644
--- a/python3/vimspector/utils.py
+++ b/python3/vimspector/utils.py
@@ -356,16 +356,21 @@ def SelectFromList( prompt, options ):
       return None
 
 
-def AskForInput( prompt, default_value = None ):
+def AskForInput( prompt, default_value = None, completion = None ):
   if default_value is None:
-    default_option = ''
-  else:
-    default_option = ", '{}'".format( Escape( default_value ) )
+    default_value = ''
+
+  args = [ prompt, default_value ]
+
+  if completion is not None:
+    if completion == 'expr':
+      args.append( 'custom,vimspector#CompleteExpr' )
+    else:
+      args.append( completion )
 
   with InputSave():
     try:
-      return vim.eval( "input( '{}' {} )".format( Escape( prompt ),
-                                                  default_option ) )
+      return Call( 'input', *args )
     except ( KeyboardInterrupt, vim.error ):
       return None
 
diff --git a/python3/vimspector/variables.py b/python3/vimspector/variables.py
index 507c495..fb9080e 100644
--- a/python3/vimspector/variables.py
+++ b/python3/vimspector/variables.py
@@ -533,7 +533,8 @@ class VariablesView( object ):
       return
 
     new_value = utils.AskForInput( 'New Value: ',
-                                   variable.variable.get( 'value', '' ) )
+                                   variable.variable.get( 'value', '' ),
+                                   completion = 'expr' )
 
     if new_value is None:
       return