diff --git a/.gitignore b/.gitignore
index 1088272..415b87d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -290,6 +290,7 @@ __pycache__/
 # Calculator specific
 Generated Files/
 src/GraphControl/GraphingImplOverrides.props
+src/CalcViewModel/DataLoaders/DataLoaderConstants.h
 !/build/config/TRexDefs/**
 !src/Calculator/TemporaryKey.pfx
 !src/CalculatorUnitTests/CalculatorUnitTests_TemporaryKey.pfx
\ No newline at end of file
diff --git a/README.md b/README.md
index 0024314..fd39861 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,12 @@ Read our [privacy statement](https://go.microsoft.com/fwlink/?LinkId=521839) to
 Telemetry is disabled in development builds by default, and can be enabled with the `SEND_TELEMETRY`
 build flag.
 
+## Currency Converter
+Windows Calculator includes a currency converter feature that uses mock data in developer builds. The data that 
+Microsoft uses for the currency converter feature (e.g., in the retail version of the application) is not licensed 
+for your use. The mock data will be clearly identifiable as it references planets instead of countries, 
+and remains static regardless of selected inputs.
+
 ## Reporting Security Issues
 Security issues and bugs should be reported privately, via email, to the
 Microsoft Security Response Center (MSRC) at <[secure@microsoft.com](mailto:secure@microsoft.com)>.
diff --git a/src/CalcViewModel/CalcViewModel.vcxproj b/src/CalcViewModel/CalcViewModel.vcxproj
index 4eaed17..c5ed5af 100644
--- a/src/CalcViewModel/CalcViewModel.vcxproj
+++ b/src/CalcViewModel/CalcViewModel.vcxproj
@@ -408,6 +408,23 @@
       <Project>{311e866d-8b93-4609-a691-265941fee101}</Project>
     </ProjectReference>
   </ItemGroup>
+  <ItemDefinitionGroup Condition="!Exists('DataLoaders\DataLoaderConstants.h')">
+    <ClCompile>
+      <AdditionalOptions>/DUSE_MOCK_DATA %(AdditionalOptions)</AdditionalOptions>
+    </ClCompile>
+  </ItemDefinitionGroup>
+  <Choose>
+	<When Condition="Exists('DataLoaders\DataLoaderConstants.h')">
+	  <ItemGroup>
+		<ClInclude Include="DataLoaders\DataLoaderConstants.h" />
+	  </ItemGroup>
+	</When>
+	<Otherwise>
+	  <ItemGroup>
+		<ClInclude Include="DataLoaders\DataLoaderMockConstants.h" />
+	  </ItemGroup>
+	</Otherwise>
+  </Choose>
   <ItemGroup>
     <None Include="DataLoaders\DefaultFromToCurrency.json" />
     <None Include="packages.config" />
diff --git a/src/CalcViewModel/CalcViewModel.vcxproj.filters b/src/CalcViewModel/CalcViewModel.vcxproj.filters
index d05aca0..bd0d75f 100644
--- a/src/CalcViewModel/CalcViewModel.vcxproj.filters
+++ b/src/CalcViewModel/CalcViewModel.vcxproj.filters
@@ -213,6 +213,12 @@
     <ClInclude Include="Common\TraceActivity.h">
       <Filter>Common</Filter>
     </ClInclude>
+    <ClInclude Include="DataLoaders\DataLoaderMockConstants.h">
+      <Filter>DataLoaders</Filter>
+    </ClInclude>
+    <ClInclude Include="DataLoaders\DataLoaderConstants.h">
+      <Filter>DataLoaders</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="DataLoaders\DefaultFromToCurrency.json">
diff --git a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
index 2fb8f0a..286422c 100644
--- a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
+++ b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
@@ -644,6 +644,23 @@ void CurrencyDataLoader::GuaranteeSelectedUnits()
             isConversionTargetSet = true;
         }
     }
+
+    // If still not set for either source or target, just select the first currency in the list
+
+    if (!m_currencyUnits.empty())
+    {
+        if (!isConversionSourceSet)
+        {
+            m_currencyUnits[0].isConversionSource = true;
+            isConversionSourceSet = true;
+        }
+
+        if (!isConversionTargetSet)
+        {
+            m_currencyUnits[0].isConversionTarget = true;
+            isConversionTargetSet = true;
+        }
+    }
 }
 
 void CurrencyDataLoader::NotifyDataLoadFinished(bool didLoad)
diff --git a/src/CalcViewModel/DataLoaders/CurrencyHttpClient.cpp b/src/CalcViewModel/DataLoaders/CurrencyHttpClient.cpp
index 04167da..e9d42c6 100644
--- a/src/CalcViewModel/DataLoaders/CurrencyHttpClient.cpp
+++ b/src/CalcViewModel/DataLoaders/CurrencyHttpClient.cpp
@@ -1,18 +1,21 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
 #include "pch.h"
 #include "CurrencyHttpClient.h"
 
+#ifdef USE_MOCK_DATA
+#include "DataLoaderMockConstants.h"
+#else
+#include "DataLoaderConstants.h"
+#endif
+
 using namespace CalculatorApp::DataLoaders;
 using namespace Platform;
 using namespace std;
 using namespace Windows::Foundation;
 using namespace Windows::Web::Http;
 
-static constexpr auto sc_MetadataUriLocalizeFor = L"https://go.microsoft.com/fwlink/?linkid=2041093&localizeFor=";
-static constexpr auto sc_RatiosUriRelativeTo = L"https://go.microsoft.com/fwlink/?linkid=2041339&localCurrency=";
-
 CurrencyHttpClient::CurrencyHttpClient()
     : m_client(ref new HttpClient())
     , m_responseLanguage(L"en-US")
diff --git a/src/CalcViewModel/DataLoaders/DataLoaderMockConstants.h b/src/CalcViewModel/DataLoaders/DataLoaderMockConstants.h
new file mode 100644
index 0000000..02e7e34
--- /dev/null
+++ b/src/CalcViewModel/DataLoaders/DataLoaderMockConstants.h
@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#pragma once
+
+namespace CalculatorApp
+{
+    namespace DataLoaders
+    {
+        static constexpr auto sc_MetadataUriLocalizeFor = L"https://go.microsoft.com/fwlink/?linkid=2091028&localizeFor=";
+        static constexpr auto sc_RatiosUriRelativeTo = L"https://go.microsoft.com/fwlink/?linkid=2091307&localCurrency=";
+    }
+}