diff --git a/1990/dg/Makefile b/1990/dg/Makefile
index 71ed320fb..15d2450f6 100644
--- a/1990/dg/Makefile
+++ b/1990/dg/Makefile
@@ -38,7 +38,7 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-invalid-pp-token -Wno-strict-prototypes
+CSILENCE= -Wno-invalid-pp-token -Wno-strict-prototypes -Wno-implicit-int
 
 # Common C compiler warning flags
 #
diff --git a/1990/dg/README.md b/1990/dg/README.md
index 247ebb880..2aa8133aa 100644
--- a/1990/dg/README.md
+++ b/1990/dg/README.md
@@ -49,23 +49,25 @@ which we have done for the wider audience.
 If my preprocessor could hack it, I could write this as one single line rather
 than 4, but when I do that I get a complaint "defines nested too deeply".
 
-Spoiler: (rot13 to read)
+### Obfuscation spoiler:
 
-    Guvf vf nabgure ebg13 wbo (oryvrir vg be abg) - gur #qrsvarf ner n
-    abiry jnl bs nqqvat gbxraf: '#qrsvar o12(k) 12 k' zrnaf gung ng
-    fbzr cbvag va gur fbhepr n 12 vf sbyybjrq ol gur pbzcerffrq arfgrq
-    qrsvarf. Gur o12 trgf gur cerivbhf pbzcerffvba nf na nethzrag, naq
-    cercraqf gur 12, guhf znxvat nabgure fgrc va gur erperngvba bs gur
-    fbhepr. Gur nkk() qrsvarf qb gur fnzr, ohg nqq gbxraf nsgre.
+This is another rot13 job (believe it or not) - the `#defines` are a
+novel way of adding tokens: `#define b12(x) 12 x` means that at
+some point in the source a `12` is followed by the compressed nested
+`#define`s. The `b12` gets the previous compression as an argument, and
+prepends the `12`, thus making another step in the recreation of the
+source. The `axx()` `#define`s do the same, but add tokens after.
 
-    Nf sbe gur ebg13 nytbevguz, vg eryvrf ba vaqrk() gb svaq vs gur
-    punenpgre vf va gur frg N-Mn-m. y[] vf na neenl gung trgf svyyrq
-    jvgu:
+As for the rot13 algorithm, it relies on `index(3)` to find if the
+character is in the set `A-Za-z`. `l[]` is an array that gets filled
+with:
 
-    "abcdefghijklmmmmnopqrstuvwxyzzzzABCDEFGHIJKLMMMMNOPQRSTUVWXYZZZZ"
+```
+"nopqrstuvwxyzzzzabcdefghijklmmmmNOPQRSTUVWXYZZZZABCDEFGHIJKLMMMM"
+```
 
-    Vs vaqrk() fnlf gur pune vf va gur nycunorg, gura kbe gur bssfrg
-    jvgu 16 gb genafyngr, naq bhgchg, bgurejvfr cnff vg hapunatrq.
+If `index(3)` says the char is in the alphabet, then XOR the offset
+with `16` to translate, and output, otherwise pass it unchanged.
 
 ## Copyright and CC BY-SA 4.0 License:
 
diff --git a/1990/dg/dg.c b/1990/dg/dg.c
index ccbb6fa29..8b1c7bae3 100644
--- a/1990/dg/dg.c
+++ b/1990/dg/dg.c
@@ -1,5 +1,7 @@
 #include <stdio.h>
 
+#define d define
+
 #define b12(x) 12 x
 #define a13(x) x 13
 #define a16(x) x 16
diff --git a/thanks-for-fixes.md b/thanks-for-fixes.md
index b8101a153..ef865b9d3 100644
--- a/thanks-for-fixes.md
+++ b/thanks-for-fixes.md
@@ -661,6 +661,26 @@ links and the user executes does that make the compiler the jury, the linker the
 judge and user the executioner? :-)
 
 
+## [1990/dg](1990/dg/dg.c) ([README.md](1990/dg/README.md]))
+
+Cody fixed this for modern systems. There were two problems to be resolved.
+
+One can no longer do:
+
+```c
+#define d define
+
+#d b12(x) 12 x
+
+/* etc. */
+```
+
+so the use of `#d` is now instead `#define` (the macro was originally deleted
+but later Cody added it back to make it more like the original).
+
+The second problem was suggested by the judges at the time of judging, to do
+with if the C preprocessor botches single quotes in cpp expansion.
+
 ## [1990/dds](1990/dds/dds.c) ([README.md](1990/dds/README.md]))
 
 Yusuke and Cody in conjunction fixed this for modern systems (both fixed a