diff --git a/extras/Build/CMake/JUCEUtils.cmake b/extras/Build/CMake/JUCEUtils.cmake
index 0c5e4672f2..1b41edc7d3 100644
--- a/extras/Build/CMake/JUCEUtils.cmake
+++ b/extras/Build/CMake/JUCEUtils.cmake
@@ -446,8 +446,12 @@ function(_juce_version_code version_in out_var)
     set(${out_var} "${hex}" PARENT_SCOPE)
 endfunction()
 
-function(_juce_to_char_literal str out_var)
-    string(APPEND str "    ") # Make sure there are at least 4 characters in the string.
+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}'")
+    endif()
 
     # Round-tripping through a file is the simplest way to convert a string to hex...
     string(SUBSTRING "${str}" 0 4 four_chars)
@@ -1137,11 +1141,11 @@ function(_juce_configure_plugin_targets target)
     get_target_property(use_legacy_compatibility_plugin_code ${target} JUCE_USE_LEGACY_COMPATIBILITY_PLUGIN_CODE)
 
     if(use_legacy_compatibility_plugin_code)
-        set(project_manufacturer_code "project_manufacturer_code-NOTFOUND")
+        set(project_manufacturer_code "proj")
     endif()
 
-    _juce_to_char_literal(${project_manufacturer_code} project_manufacturer_code)
-    _juce_to_char_literal(${project_plugin_code} project_plugin_code)
+    _juce_to_char_literal(${project_manufacturer_code} project_manufacturer_code "plugin manufacturer")
+    _juce_to_char_literal(${project_plugin_code} project_plugin_code "plugin")
 
     _juce_get_vst3_category_string(${target} vst3_category_string)
 
diff --git a/extras/Projucer/Source/Project/jucer_Project.cpp b/extras/Projucer/Source/Project/jucer_Project.cpp
index 7b9ef80b7e..32e6fd0a58 100644
--- a/extras/Projucer/Source/Project/jucer_Project.cpp
+++ b/extras/Projucer/Source/Project/jucer_Project.cpp
@@ -2579,7 +2579,7 @@ StringPairArray Project::getAudioPluginFlags() const
 
         for (int i = 0; i < 4; ++i)
             hexRepresentation = (hexRepresentation << 8u)
-                                |  (static_cast<unsigned int> (fourCharCode[i]) & 0xffu);
+                                | (static_cast<unsigned int> (fourCharCode[i]) & 0xffu);
 
         return "0x" + String::toHexString (static_cast<int> (hexRepresentation));
     };
diff --git a/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp b/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
index d18b649406..e4dd8d0037 100644
--- a/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
+++ b/extras/Projucer/Source/ProjectSaving/jucer_ProjectSaver.cpp
@@ -292,6 +292,20 @@ 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())