diff --git a/README.md b/README.md
index 3d5db33c..ab722519 100644
--- a/README.md
+++ b/README.md
@@ -414,6 +414,12 @@ argument) that further describes the error. The error code is always set
 even if an error callback function is registered. It is recommended to
 always set a error callback function, to detect all errors.
 
+When the device construction fails, `oidnNewDevice` returns `NULL` as
+device. To detect the error code of a such failed device construction,
+pass `NULL` as device to the `oidnGetDeviceError` function. For all
+other invocations of `oidnGetDeviceError`, a proper device handle must
+be specified.
+
 The following errors are currently used by Open Image
 Denoise:
 
diff --git a/doc/api.md b/doc/api.md
index a719d9e7..fb8b41c6 100644
--- a/doc/api.md
+++ b/doc/api.md
@@ -194,6 +194,11 @@ the error code (`code` argument) of the occurred error, as well as a string
 set even if an error callback function is registered. It is recommended to
 always set a error callback function, to detect all errors.
 
+When the device construction fails, `oidnNewDevice` returns `NULL` as device.
+To detect the error code of a such failed device construction, pass `NULL` as
+device to the `oidnGetDeviceError` function. For all other invocations of
+`oidnGetDeviceError`, a proper device handle must be specified.
+
 The following errors are currently used by Open Image Denoise:
 
 ------------------------------- -----------------------------------------------
diff --git a/readme.pdf b/readme.pdf
new file mode 100644
index 00000000..dc7f51e2
Binary files /dev/null and b/readme.pdf differ