diff --git a/src/store/MemoryStore.js b/src/store/MemoryStore.js
index 52786f4..d4b92da 100644
--- a/src/store/MemoryStore.js
+++ b/src/store/MemoryStore.js
@@ -19,8 +19,9 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-var Class = require( 'easejs' ).Class,
-    Store = require( './Store' );
+var Class          = require( 'easejs' ).Class,
+    Store          = require( './Store' ),
+    StoreMissError = require( './StoreMissError' );
 
 
 /**
@@ -107,7 +108,9 @@ module.exports = Class( 'MemoryStore' )
     {
         return ( this._store[ key ] !== undefined )
             ? Promise.resolve( this._store[ key ] )
-            : Promise.reject( 'Key ' + key + ' does not exist' );
+            : Promise.reject(
+                StoreMissError( "Key '" + key + "' does not exist" )
+            );
     },
 
 
diff --git a/src/store/StoreMissError.js b/src/store/StoreMissError.js
new file mode 100644
index 0000000..8017fdb
--- /dev/null
+++ b/src/store/StoreMissError.js
@@ -0,0 +1,31 @@
+/**
+ * Error when key is not found in store
+ *
+ *  Copyright (C) 2016 LoVullo Associates, Inc.
+ *
+ *  This file is part of the Liza Data Collection Framework
+ *
+ *  Liza is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+var Class = require( 'easejs' ).Class;
+
+
+/**
+ * Store key miss
+ *
+ * A key was not found in a store.
+ */
+module.exports = Class( 'StoreMissError' )
+    .extend( ReferenceError, {} );
diff --git a/test/store/MemoryStoreTest.js b/test/store/MemoryStoreTest.js
index 82392af..7d47bc2 100644
--- a/test/store/MemoryStoreTest.js
+++ b/test/store/MemoryStoreTest.js
@@ -78,7 +78,8 @@ describe( 'store.MemoryStore', () =>
         it( 'rejects promise if store item does not exist', () =>
         {
             return expect( Sut().get( 'unknown' ) )
-                .to.eventually.be.rejected;
+                .to.eventually.be.rejected
+                .and.be.instanceof( store.StoreMissError );
         } );
     } );