diff --git a/callisto.c b/callisto.c
index 8521201..ed97f68 100644
--- a/callisto.c
+++ b/callisto.c
@@ -1,5 +1,6 @@
 /*
- * callisto - standalone scripting platform for Lua 5.4
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
  */
 
 #include <lua.h>
diff --git a/callisto.h b/callisto.h
index c26eb36..6f7ac25 100644
--- a/callisto.h
+++ b/callisto.h
@@ -1,5 +1,6 @@
 /*
- * callisto - standalone scripting platform for Lua 5.4
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
  */
 
 #ifndef _CALLISTO_H_
diff --git a/csto.c b/csto.c
index f075f0e..16d8067 100644
--- a/csto.c
+++ b/csto.c
@@ -1,5 +1,7 @@
 /*
- * csto: The Callisto stand-alone interpreter
+ * csto: the Callisto stand-alone interpreter
+ * Copyright (c) 1994-2023 Lua.org, PUC-Rio.
+ * Copyright (c) 2023-2024 Jeremy Baxter.
  */
 
 #include <stdio.h>
diff --git a/lcl.c b/lcl.c
index c889384..088e565 100644
--- a/lcl.c
+++ b/lcl.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Option parsing, and error formatting
  * for the command line.
diff --git a/lenviron.c b/lenviron.c
index 18405b1..cc9e127 100644
--- a/lenviron.c
+++ b/lenviron.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Getting and setting environment variables.
  * @module environ
diff --git a/lextra.c b/lextra.c
index ecf16bc..3efabe9 100644
--- a/lextra.c
+++ b/lextra.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Extra functions that don't fit into any other category.
  *
diff --git a/lfs.c b/lfs.c
index dfef0e1..b481ed8 100644
--- a/lfs.c
+++ b/lfs.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Files, directories and file system manipulation.
  *
diff --git a/ljson.c b/ljson.c
index 2d0a4dc..51880a3 100644
--- a/ljson.c
+++ b/ljson.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Manipulation of JavaScript Object Notation (JSON) values.
  *
diff --git a/lprocess.c b/lprocess.c
index deedac2..1148ce9 100644
--- a/lprocess.c
+++ b/lprocess.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /***
  * Processes, signals, and signal handlers.
  *
diff --git a/util.c b/util.c
index 0688ecb..38145e7 100644
--- a/util.c
+++ b/util.c
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 /*
  * util.c
  *
diff --git a/util.h b/util.h
index 4a9e2da..5b22119 100644
--- a/util.h
+++ b/util.h
@@ -1,3 +1,8 @@
+/*
+ * Callisto - standalone scripting platform for Lua 5.4
+ * Copyright (c) 2023-2024 Jeremy Baxter.
+ */
+
 #ifndef _UTIL_H_
 
 #define _UTIL_H_