diff --git a/web/content/docs/devguide/advanced/log-and-debug-output.pandoc b/web/content/docs/devguide/advanced/log-and-debug-output.pandoc
index 8bf61dda3dfb449ba37b6e71a9f10c8691d70094..427e2013f01eb1c2d02703d5c51674c7ba62791e 100644
--- a/web/content/docs/devguide/advanced/log-and-debug-output.pandoc
+++ b/web/content/docs/devguide/advanced/log-and-debug-output.pandoc
@@ -11,25 +11,28 @@ weight = 1034
 
 ## Introduction
 
-For application output we use [Logog](http://johnwbyrd.github.com/logog) which is already integrated in OGS. Logog provides several verbosity levels which can be used with simple macro calls:
+For application output we use [spdlog](https://github.com/gabime/spdlog) which
+is already integrated in OGS. Spdlog provides several verbosity levels which can
+be used with simple calls:
 
 ```cpp
-ERR("An error message!")
-WARN("A warning message.")
-INFO("An information message...")
+ERR("An error message!");
+WARN("A warning message.");
+INFO("An information message...");
+DBUG("A debug message.");
 ```
 
-As arguments you can use the same functionality as in [sprintf](http://www.cplusplus.com/reference/cstdio/sprintf/):
+As arguments you can use the same functionality as in [fmt](https://fmt.dev)---a
+modern formatting library:
 
 ```cpp
-int foo = 9001;
-int maxfoo = 9000;
-if (foo > maxfoo)
-    WARN("Foo is over %d!  Current value is %d.", maxfoo, foo );
+int foo = 42;
+double boo = 3.14;
+WARN("Foo is {}! Current value is {:10.2g}.", foo, boo);
 ```
 
-For more information see the [Logog documentation](http://johnwbyrd.github.com/logog/quickstart.html).
-
+For more information see the [spdlog
+wiki](https://github.com/gabime/spdlog/wiki).
 
 On release builds the default log level is `INFO`, for debug builds it is
 `DEBUG`.