Right, I'm committing this session because I'm too cold and tired to go on.

It does not at present build (and it's going to take a good bit more work
before it does).

src/c/payloads/psse_string.c

@@ -8,23 +8,19 @@
  */
 
 
-#include <stdint.h>
 
  /*
   * wide characters
   */
-#include <wchar.h>
-#include <wctype.h>
 
 #include "memory/node.h"
 #include "memory/pointer.h"
 #include "memory/pso.h"
-#include "memory/pso2.h"
 #include "memory/pso4.h"
 #include "memory/tags.h"
 
-#include "ops/string_ops.h"
-#include "ops/truth.h"
+#include "payloads/cons.h"
+
 
 /**
  * @brief When an string is freed, its cdr pointer must be decremented.
@@ -38,7 +34,7 @@ struct pso_pointer destroy_string( struct pso_pointer fp,
         struct pso4 *frame = pointer_to_pso4( fp );
         struct pso_pointer p = frame->payload.stack_frame.arg[0];
 
-        dec_ref( c_cdr( p ) );
+        dec_ref( c_cdr( frame, p ) );
     }
 
     return nil;