diff --git a/lib/gcli/languages/command.js b/lib/gcli/languages/command.js
index f423a8e4..bc9f4381 100644
--- a/lib/gcli/languages/command.js
+++ b/lib/gcli/languages/command.js
@@ -184,7 +184,7 @@ var commandLanguage = exports.commandLanguage = {
       var isNew = (this.assignment !== newAssignment);
 
       this.assignment = newAssignment;
-      this.terminal.updateCompletion();
+      this.terminal.updateCompletion().then(null, util.errorHandler);
 
       if (isNew) {
         this.updateHints();
@@ -286,7 +286,7 @@ var commandLanguage = exports.commandLanguage = {
     }
 
     this.terminal.history.add(input);
-    this.terminal.unsetChoice();
+    this.terminal.unsetChoice().then(null, util.errorHandler);
 
     return this.requisition.exec().then(function() {
       this.textChanged();
diff --git a/lib/gcli/languages/languages.js b/lib/gcli/languages/languages.js
index 49e0f1ec..738c7f94 100644
--- a/lib/gcli/languages/languages.js
+++ b/lib/gcli/languages/languages.js
@@ -51,8 +51,9 @@ var baseLanguage = {
   },
 
   handleTab: function() {
-    this.terminal.unsetChoice();
-    return RESOLVED;
+    return this.terminal.unsetChoice().then(function() {
+      return RESOLVED;
+    }, util.errorHandler);
   },
 
   handleInput: function(input) {
@@ -62,8 +63,9 @@ var baseLanguage = {
       }.bind(this));
     }
 
-    this.terminal.unsetChoice();
-    return RESOLVED;
+    return this.terminal.unsetChoice().then(function() {
+      return RESOLVED;
+    }, util.errorHandler);
   },
 
   handleReturn: function(input) {
@@ -80,7 +82,7 @@ var baseLanguage = {
 
       this.focusManager.outputted();
 
-      this.terminal.unsetChoice();
+      this.terminal.unsetChoice().then(null, util.errorHandler);
       this.terminal.inputElement.value = '';
     }.bind(this));
   },
diff --git a/lib/gcli/ui/terminal.js b/lib/gcli/ui/terminal.js
index fb2bbaa6..0c68e9a1 100644
--- a/lib/gcli/ui/terminal.js
+++ b/lib/gcli/ui/terminal.js
@@ -150,7 +150,7 @@ Terminal.prototype._init = function(system, options, terminalCss, terminalHtml)
   this.focusManager.addMonitoredElement(this.tooltipElement, 'tooltip');
   this.focusManager.addMonitoredElement(this.inputElement, 'input');
 
-  this.onInputChange.add(this.updateCompletion, this);
+  this.onInputChange.add(this._updateCompletionWithErrorHandler, this);
 
   host.script.onOutput.add(this.onOutput);
 
@@ -185,7 +185,7 @@ Terminal.prototype.destroy = function() {
   this.field.onFieldChange.remove(this.fieldChanged, this);
   this.field.destroy();
 
-  this.onInputChange.remove(this.updateCompletion, this);
+  this.onInputChange.remove(this._updateCompletionWithErrorHandler, this);
 
   // Remove the output elements so they free the event handers
   util.clearElement(this.displayElement);
@@ -265,7 +265,7 @@ Terminal.prototype._updateLanguage = function(language) {
   }
 
   this.language.updateHints();
-  this.updateCompletion();
+  this.updateCompletion().then(null, util.errorHandler);
   this.promptElement.innerHTML = this.language.prompt;
 };
 
@@ -584,6 +584,14 @@ Terminal.prototype.updateCompletion = function() {
   }.bind(this));
 };
 
+/**
+ * Call updateCompletion, but log if something is wrong. To be called by
+ * event handlers that can't react to rejected promises.
+ */
+Terminal.prototype._updateCompletionWithErrorHandler = function() {
+  this.updateCompletion().then(null, util.errorHandler);
+};
+
 /**
  * The terminal acts on UP/DOWN if there is a menu showing
  */