diff --git a/2019/duble/Makefile b/2019/duble/Makefile
index 763b9cfe4..3953508ca 100644
--- a/2019/duble/Makefile
+++ b/2019/duble/Makefile
@@ -137,6 +137,8 @@ all: data ${TARGET}
 
 ${PROG}:
 	${MAKE} `${UNAME}`
+	@echo "WARNING: this entry will likely leave sockets lying about in the current"
+	@echo "working directory. See the bugs.md and README.md for details."
 
 check-os: check-os.sh
 	${SHELL} ./check-os.sh ${LINES} ${COLUMNS}
diff --git a/2019/duble/README.md b/2019/duble/README.md
index 754ea6906..9b04f3b9d 100644
--- a/2019/duble/README.md
+++ b/2019/duble/README.md
@@ -33,6 +33,17 @@ WARNING: if the file is deleted it might lock any session still in use. These
 will have to be killed from another shell session or by closing the terminal
 tab.
 
+NOTE: this entry might leave sockets lying about in the current working
+directory which you'll have to delete manually. Here's an example in macOS:
+
+```sh
+$ ls -al
+srwxr-xr-x   1 ioccc  staff      0  6 Apr 08:19 .BDHFHALG
+srwxr-xr-x   1 ioccc  staff      0  6 Apr 08:15 .CGGHAMGC
+srwxr-xr-x   1 ioccc  staff      0  6 Apr 08:16 .CMDGAELH
+...
+```
+
 ### Alternate code:
 
 An alternate version of this entry, [prog.alt.c](prog.alt.c), is provided.  This alternate
@@ -48,8 +59,8 @@ Use `prog.alt` as you would `prog` above.
 
 ## Judges' remarks:
 
-After starting the program, use the cursor keys, then try some modes, like "p"
-or "l" (they toggle).
+After starting the program, use the cursor keys, then try some modes, like `p`
+or `l` (they toggle).
 
 ## Author's remarks:
 
@@ -69,13 +80,15 @@ To build, type `make` (assuming gcc) or `make CC=clang`.
 
 Then you can start the program. It expects a file path as its first argument:
 
-    $ ./prog /tmp/drawing
+```sh
+./prog /tmp/drawing
+```
 
 (If not started this way, `prog` will refuse to start.)
 
 If the file does not exist, you will start with a blank drawing.
 
-If someone else (or another *instance of yourself*, maybe??) is already
+If someone else (or another *instance of yourself*, maybe?) is already
 editing this file, you will join the session!
 
 ### Edition features:
diff --git a/bugs.md b/bugs.md
index a84117db6..1deb29dcd 100644
--- a/bugs.md
+++ b/bugs.md
@@ -2066,6 +2066,26 @@ but this is expected and the file `ioccc.html` will be generated properly.
 
 # 2019
 
+## [2019/duble](2019/duble/prog.c) ([README.md](2019/duble/README.md)
+## STATUS: INABIAF - please **DO NOT** fix
+
+This program will very likely leave sockets lying about in the current working
+directory. For instance [Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson)
+showed us this:
+
+```sh
+$ ls -al |grep '^s'
+srwxr-xr-x   1 cody  staff     0 Apr  6 08:19 .BDHFHALG=
+srwxr-xr-x   1 cody  staff     0 Apr  6 08:15 .CGGHAMGC=
+srwxr-xr-x   1 cody  staff     0 Apr  6 08:16 .CMDGAELH=
+srwxr-xr-x   1 cody  staff     0 Apr  3 08:47 .CMLBCCDA=
+[...]
+```
+
+This is NOT a bug and you'll have to (at least at this time?) delete the files
+manually. You shouldn't have to worry about these being added to git: it seems
+to ignore sockets (it did at least in macOS).
+
 ## [2019/ciura](2019/ciura/prog.c) ([README.md](2019/ciura/README.md))
 ## STATUS: known bug - please help us fix