diff --git a/README.md b/README.md
index 55bddf9b..0dbe3e65 100644
--- a/README.md
+++ b/README.md
@@ -30,20 +30,26 @@ which is based on OpenIddict, comes with sensible defaults and offers a built-in
 
 ## Compatibility matrix
 
-| Web framework version | .NET runtime version | OpenIddict 2.0     | OpenIddict 2.0.1   | OpenIddict 3.0     |
-|-----------------------|----------------------|--------------------|--------------------|--------------------|
-| ASP.NET Core 2.1      | .NET Framework 4.6.1 | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| ASP.NET Core 2.1      | .NET Framework 4.7.2 | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| ASP.NET Core 2.1      | .NET Framework 4.8   | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| ASP.NET Core 2.1      | .NET Core 2.1        | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-|                       |                      |                    |                    |                    |
-| ASP.NET Core 3.1      | .NET Core 3.1        | :warning:          | :heavy_check_mark: | :heavy_check_mark: |
-|                       |                      |                    |                    |                    |
-| ASP.NET Core 5.0      | .NET 5.0             | :warning:          | :heavy_check_mark: | :heavy_check_mark: |
-|                       |                      |                    |                    |                    |
-| OWIN/Katana 4.1       | .NET Framework 4.6.1 | :x:                | :x:                | :heavy_check_mark: |
-| OWIN/Katana 4.1       | .NET Framework 4.7.2 | :x:                | :x:                | :heavy_check_mark: |
-| OWIN/Katana 4.1       | .NET Framework 4.8   | :x:                | :x:                | :heavy_check_mark: |
+| Web framework version | .NET runtime version | OpenIddict 2.0                          | OpenIddict 2.0.1                        | OpenIddict 3.0                          |
+|-----------------------|----------------------|-----------------------------------------|-----------------------------------------|-----------------------------------------|
+| ASP.NET Core 2.1      | .NET Framework 4.6.1 | :heavy_check_mark: :information_source: | :heavy_check_mark: :information_source: | :heavy_check_mark: :information_source: |
+| ASP.NET Core 2.1      | .NET Framework 4.7.2 | :heavy_check_mark:                      | :heavy_check_mark:                      | :heavy_check_mark:                      |
+| ASP.NET Core 2.1      | .NET Framework 4.8   | :heavy_check_mark:                      | :heavy_check_mark:                      | :heavy_check_mark:                      |
+| ASP.NET Core 2.1      | .NET Core 2.1        | :heavy_check_mark:                      | :heavy_check_mark:                      | :heavy_check_mark:                      |
+|                       |                      |                                         |                                         |                                         |
+| ASP.NET Core 3.1      | .NET Core 3.1        | :warning:                               | :heavy_check_mark:                      | :heavy_check_mark:                      |
+|                       |                      |                                         |                                         |                                         |
+| ASP.NET Core 5.0      | .NET 5.0             | :warning:                               | :heavy_check_mark:                      | :heavy_check_mark:                      |
+|                       |                      |                                         |                                         |                                         |
+| OWIN/Katana 4.1       | .NET Framework 4.6.1 | :x:                                     | :x:                                     | :heavy_check_mark: :information_source: |
+| OWIN/Katana 4.1       | .NET Framework 4.7.2 | :x:                                     | :x:                                     | :heavy_check_mark:                      |
+| OWIN/Katana 4.1       | .NET Framework 4.8   | :x:                                     | :x:                                     | :heavy_check_mark:                      |
+
+:information_source: **Note: the following features are not available when targeting .NET Framework 4.6.1**:
+ - X.509 development encryption/signing certificates: calling `AddDevelopmentEncryptionCertificate()` or `AddDevelopmentSigningCertificate()`
+will result in a `PlatformNotSupportedException` being thrown at runtime if no valid development certificate can be found and a new one must be generated.
+ - X.509 ECDSA signing certificates/keys: calling `AddSigningCertificate()` or `AddSigningKey()`
+with an ECDSA certificate/key will always result in a `PlatformNotSupportedException` being thrown at runtime.
 
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