diff --git a/extras/Build/CMake/JUCEUtils.cmake b/extras/Build/CMake/JUCEUtils.cmake
index a734f2dae1..151a759657 100644
--- a/extras/Build/CMake/JUCEUtils.cmake
+++ b/extras/Build/CMake/JUCEUtils.cmake
@@ -451,7 +451,7 @@ function(_juce_to_char_literal str out_var help_text)
     string(LENGTH "${str}" string_length)
 
     if(NOT "${string_length}" EQUAL "4")
-        message(FATAL_ERROR "The ${help_text} code must contain exactly four characters, but it was set to '${str}'")
+        message(WARNING "The ${help_text} code must contain exactly four characters, but it was set to '${str}'")
     endif()
 
     # Round-tripping through a file is the simplest way to convert a string to hex...
@@ -463,7 +463,8 @@ function(_juce_to_char_literal str out_var help_text)
     file(READ "${scratch_file}" four_chars_hex HEX)
     file(REMOVE "${scratch_file}")
 
-    set(${out_var} ${four_chars_hex} PARENT_SCOPE)
+    string(SUBSTRING "${four_chars_hex}00000000" 0 8 four_chars_hex)
+    set(${out_var} "${four_chars_hex}" PARENT_SCOPE)
 endfunction()
 
 # ==================================================================================================
diff --git a/extras/Projucer/Source/Project/jucer_Project.cpp b/extras/Projucer/Source/Project/jucer_Project.cpp
index fd69c0985c..28dc55f4d7 100644
--- a/extras/Projucer/Source/Project/jucer_Project.cpp
+++ b/extras/Projucer/Source/Project/jucer_Project.cpp
@@ -826,6 +826,14 @@ void Project::updateJUCEPathWarning()
     }
 }
 
+void Project::updateCodeWarning (Identifier identifier, String value)
+{
+    if (value.length() != 4 || value.toStdString().size() != 4)
+        addProjectMessage (identifier, {});
+    else
+        removeProjectMessage (identifier);
+}
+
 void Project::updateModuleWarnings()
 {
     auto& modules = getEnabledModules();
@@ -1091,6 +1099,14 @@ void Project::valueTreePropertyChanged (ValueTree& tree, const Identifier& prope
         {
             updateModuleWarnings();
         }
+        else if (property == Ids::pluginCode)
+        {
+            updateCodeWarning (ProjectMessages::Ids::pluginCodeInvalid, pluginCodeValue.get());
+        }
+        else if (property == Ids::pluginManufacturerCode)
+        {
+            updateCodeWarning (ProjectMessages::Ids::manufacturerCodeInvalid, pluginManufacturerCodeValue.get());
+        }
     }
 
     changed();
@@ -2578,8 +2594,10 @@ StringPairArray Project::getAudioPluginFlags() const
         uint32 hexRepresentation = 0;
 
         for (int i = 0; i < 4; ++i)
-            hexRepresentation = (hexRepresentation << 8u)
-                                | (static_cast<unsigned int> (fourCharCode[i]) & 0xffu);
+        {
+            const auto character = (unsigned int) (i < fourCharCode.length() ? fourCharCode[i] : 0);
+            hexRepresentation = (hexRepresentation << 8u) | (character & 0xffu);
+        }
 
         return "0x" + String::toHexString (static_cast<int> (hexRepresentation));
     };
diff --git a/extras/Projucer/Source/Project/jucer_Project.h b/extras/Projucer/Source/Project/jucer_Project.h
index a02a01a45a..8f1a3a91f9 100644
--- a/extras/Projucer/Source/Project/jucer_Project.h
+++ b/extras/Projucer/Source/Project/jucer_Project.h
@@ -50,6 +50,8 @@ namespace ProjectMessages
         DECLARE_ID (oldProjucer);
         DECLARE_ID (cLion);
         DECLARE_ID (newVersionAvailable);
+        DECLARE_ID (pluginCodeInvalid);
+        DECLARE_ID (manufacturerCodeInvalid);
 
         DECLARE_ID (notification);
         DECLARE_ID (warning);
@@ -63,7 +65,7 @@ namespace ProjectMessages
     {
         static Identifier warnings[] = { Ids::incompatibleLicense, Ids::cppStandard, Ids::moduleNotFound,
                                          Ids::jucePath, Ids::jucerFileModified, Ids::missingModuleDependencies,
-                                         Ids::oldProjucer, Ids::cLion };
+                                         Ids::oldProjucer, Ids::cLion, Ids::pluginCodeInvalid, Ids::manufacturerCodeInvalid };
 
         if (std::find (std::begin (warnings), std::end (warnings), message) != std::end (warnings))
             return Ids::warning;
@@ -86,6 +88,8 @@ namespace ProjectMessages
         if (message == Ids::oldProjucer)                return "Projucer Out of Date";
         if (message == Ids::newVersionAvailable)        return "New Version Available";
         if (message == Ids::cLion)                      return "Deprecated Exporter";
+        if (message == Ids::pluginCodeInvalid)          return "Invalid Plugin Code";
+        if (message == Ids::manufacturerCodeInvalid)    return "Invalid Manufacturer Code";
 
         jassertfalse;
         return {};
@@ -102,6 +106,8 @@ namespace ProjectMessages
         if (message == Ids::oldProjucer)                return "The version of the Projucer you are using is out of date.";
         if (message == Ids::newVersionAvailable)        return "A new version of JUCE is available to download.";
         if (message == Ids::cLion)                      return "The CLion exporter is deprecated. Use JUCE's CMake support instead.";
+        if (message == Ids::pluginCodeInvalid)          return "The plugin code should be exactly four characters in length.";
+        if (message == Ids::manufacturerCodeInvalid)    return "The manufacturer code should be exactly four characters in length.";
 
         jassertfalse;
         return {};
@@ -618,6 +624,7 @@ private:
     void updateOldProjucerWarning (bool showWarning);
     void updateCLionWarning (bool showWarning);
     void updateModuleNotFoundWarning (bool showWarning);
+    void updateCodeWarning (Identifier identifier, String value);
 
     ValueTree projectMessages { ProjectMessages::Ids::projectMessages, {},
                                 { { ProjectMessages::Ids::notification, {} }, { ProjectMessages::Ids::warning, {} } } };
diff --git a/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp b/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
index fcfa71b003..f61cf2e4a6 100644
--- a/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
+++ b/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
@@ -291,20 +291,6 @@ Result ProjectSaver::saveProject (ProjectExporter* specifiedExporterToSave)
 
     if (errors.isEmpty())
     {
-        if (project.isAudioPluginProject())
-        {
-            const auto isInvalidCode = [] (String code)
-            {
-                return code.length() != 4 || code.toStdString().size() != 4;
-            };
-
-            if (isInvalidCode (project.getPluginManufacturerCodeString()))
-                return Result::fail ("The plugin manufacturer code must contain exactly four characters.");
-
-            if (isInvalidCode (project.getPluginCodeString()))
-                return Result::fail ("The plugin code must contain exactly four characters.");
-        }
-
         if (project.isAudioPluginProject())
         {
             if (project.shouldBuildUnityPlugin())