diff --git a/buffet/commands/prop_constraints.cc b/buffet/commands/prop_constraints.cc
index 97b524d..210b254 100644
--- a/buffet/commands/prop_constraints.cc
+++ b/buffet/commands/prop_constraints.cc
@@ -12,37 +12,42 @@
 // Constraint ----------------------------------------------------------------
 Constraint::~Constraint() {}
 
-bool Constraint::ReportErrorLessThan(
-    ErrorPtr* error, const std::string& val, const std::string& limit) {
-  Error::AddToPrintf(error, errors::commands::kDomain,
-                     errors::commands::kOutOfRange,
-                     "Value %s is out of range. It must not be less than %s",
-                     val.c_str(), limit.c_str());
+bool Constraint::ReportErrorLessThan(chromeos::ErrorPtr* error,
+                                     const std::string& val,
+                                     const std::string& limit) {
+  chromeos::Error::AddToPrintf(
+      error, errors::commands::kDomain,
+      errors::commands::kOutOfRange,
+      "Value %s is out of range. It must not be less than %s",
+      val.c_str(), limit.c_str());
   return false;
 }
 
-bool Constraint::ReportErrorGreaterThan(
-    ErrorPtr* error, const std::string& val, const std::string& limit) {
-  Error::AddToPrintf(error, errors::commands::kDomain,
-                     errors::commands::kOutOfRange,
-                     "Value %s is out of range. It must not be greater than %s",
-                     val.c_str(), limit.c_str());
+bool Constraint::ReportErrorGreaterThan(chromeos::ErrorPtr* error,
+                                        const std::string& val,
+                                        const std::string& limit) {
+  chromeos::Error::AddToPrintf(
+      error, errors::commands::kDomain,
+      errors::commands::kOutOfRange,
+      "Value %s is out of range. It must not be greater than %s",
+      val.c_str(), limit.c_str());
   return false;
 }
 
-bool Constraint::ReportErrorNotOneOf(
-    ErrorPtr* error, const std::string& val,
-    const std::vector<std::string>& values) {
-  Error::AddToPrintf(error, errors::commands::kDomain,
-                     errors::commands::kOutOfRange,
-                     "Value %s is invalid. Expected one of [%s]",
-                     val.c_str(), string_utils::Join(',', values).c_str());
+bool Constraint::ReportErrorNotOneOf(chromeos::ErrorPtr* error,
+                                     const std::string& val,
+                                     const std::vector<std::string>& values) {
+  chromeos::Error::AddToPrintf(error, errors::commands::kDomain,
+                               errors::commands::kOutOfRange,
+                               "Value %s is invalid. Expected one of [%s]",
+                               val.c_str(),
+                               string_utils::Join(',', values).c_str());
   return false;
 }
 
 bool Constraint::AddToJsonDict(base::DictionaryValue* dict,
                                bool overridden_only,
-                               ErrorPtr* error) const {
+                               chromeos::ErrorPtr* error) const {
   if (!overridden_only || HasOverriddenAttributes()) {
     auto value = ToJson(error);
     if (!value)
@@ -62,7 +67,7 @@
 }
 
 std::unique_ptr<base::Value> ConstraintStringLength::ToJson(
-    ErrorPtr* error) const {
+    chromeos::ErrorPtr* error) const {
   return TypedValueToJson(limit_.value, error);
 }
 
@@ -73,20 +78,21 @@
     : ConstraintStringLength(limit) {}
 
 bool ConstraintStringLengthMin::Validate(const PropValue& value,
-                                         ErrorPtr* error) const {
+                                         chromeos::ErrorPtr* error) const {
   CHECK(value.GetString()) << "Expecting a string value for this constraint";
   const std::string& str = value.GetString()->GetValue();
   int length = static_cast<int>(str.size());
   if (length < limit_.value) {
     if (limit_.value == 1) {
-      Error::AddTo(error, errors::commands::kDomain,
-                   errors::commands::kOutOfRange, "String must not be empty");
+      chromeos::Error::AddTo(error, errors::commands::kDomain,
+                             errors::commands::kOutOfRange,
+                             "String must not be empty");
     } else {
-      Error::AddToPrintf(error, errors::commands::kDomain,
-                         errors::commands::kOutOfRange,
-                         "String must be at least %d characters long, "
-                         "actual length of string '%s' is %d", limit_.value,
-                         str.c_str(), length);
+      chromeos::Error::AddToPrintf(error, errors::commands::kDomain,
+                                   errors::commands::kOutOfRange,
+                                   "String must be at least %d characters long,"
+                                   " actual length of string '%s' is %d",
+                                   limit_.value, str.c_str(), length);
     }
     return false;
   }
@@ -105,16 +111,16 @@
     : ConstraintStringLength(limit) {}
 
 bool ConstraintStringLengthMax::Validate(const PropValue& value,
-                                         ErrorPtr* error) const {
+                                         chromeos::ErrorPtr* error) const {
   CHECK(value.GetString()) << "Expecting a string value for this constraint";
   const std::string& str = value.GetString()->GetValue();
   int length = static_cast<int>(str.size());
   if (length > limit_.value) {
-    Error::AddToPrintf(error, errors::commands::kDomain,
-                       errors::commands::kOutOfRange,
-                       "String must be no more than %d character(s) long, "
-                       "actual length of string '%s' is %d", limit_.value,
-                       str.c_str(), length);
+    chromeos::Error::AddToPrintf(error, errors::commands::kDomain,
+                                 errors::commands::kOutOfRange,
+                                 "String must be no more than %d character(s) "
+                                 "long, actual length of string '%s' is %d",
+                                 limit_.value, str.c_str(), length);
     return false;
   }
   return true;