diff --git a/reference/exec/functions/proc-open.xml b/reference/exec/functions/proc-open.xml
index 2b87c8f906..f5578ce5ad 100644
--- a/reference/exec/functions/proc-open.xml
+++ b/reference/exec/functions/proc-open.xml
@@ -49,6 +49,20 @@
The command to execute
+
+
+ On Windows, unless bypass_shell is set to &true; in
+ other_options, the cmd is
+ passed to cmd.exe (actually, %ComSpec%)
+ with the /c flag as unquoted string
+ (i.e. exactly as has been given to proc_open).
+ This can cause cmd.exe to remove enclosing quotes from
+ cmd (for details see the cmd.exe documentation),
+ resulting in unexpected, and potentially even dangerous behavior, because
+ cmd.exe error messages may contain (parts of) the passed
+ cmd (see example below).
+
+
@@ -250,6 +264,43 @@ command returned 0
+
+
+ proc_open quirk on Windows
+
+ While one may expect the following program to search the file
+ filename.txt for the text search and
+ to print the results, it behaves rather differently.
+
+
+
+]]>
+
+ &example.outputs;
+
+
+
+
+ To work around that behavior, it is usually sufficient to enclose the
+ cmd in additional quotes:
+
+
+
+
+
+
+