diff --git a/lisp/c/sysfunc.c b/lisp/c/sysfunc.c
index 3e7bdec60..3a7c5a6be 100644
--- a/lisp/c/sysfunc.c
+++ b/lisp/c/sysfunc.c
@@ -687,6 +687,20 @@ pointer argv[];
 /* stack frame access
 /* 1988-Apr-26
 /****************************************************************/
+pointer LISTALLBLOCKS(ctx,n,argv)
+register context *ctx;
+int n;
+pointer *argv;
+{ pointer blocks=NIL;
+  struct blockframe *bfp=ctx->blkfp;
+  int i=0;
+  while (bfp) {
+    if (bfp->kind==BLOCKFRAME) {
+      vpush(bfp->name);
+      i++;}
+    bfp=bfp->lexklink;}
+  return(stacknlist(ctx,i));}
+
 pointer LISTALLCATCHERS(ctx,n,argv)
 register context *ctx;
 int n;
@@ -799,6 +813,7 @@ pointer mod;
 /*  defun(ctx,"MALLOC_DEBUG",mod,MALLOC_DEBUG,NULL);
 /*  defun(ctx,"MALLOC_VERIFY",mod,MALLOC_VERIFY,NULL); */
   defun(ctx,"LIST-ALL-REFERENCES",mod,LISTALLREFERENCES,NULL);
+  defun(ctx,"LIST-ALL-BLOCKS",mod,LISTALLBLOCKS,NULL);
   defun(ctx,"LIST-ALL-CATCHERS",mod,LISTALLCATCHERS,NULL);
   defun(ctx,"LIST-ALL-BINDINGS",mod,LISTBINDINGS,NULL);
   defun(ctx,"LIST-ALL-SPECIAL-BINDINGS",mod,LISTSPECIALBINDINGS,NULL);
diff --git a/lisp/l/eusstart.l b/lisp/l/eusstart.l
index 4478db5ac..f7c0f2a91 100644
--- a/lisp/l/eusstart.l
+++ b/lisp/l/eusstart.l
@@ -175,7 +175,7 @@
 	  ALLOC  NEWSTACK  RECLAIM  RECLAIM-TREE
 	  OBJECT-SIZE  MEMORY-REPORT  CLEAR-MEMORY-REPORT
 	  ROOM  LIST-ALL-CHUNKS  LIST-ALL-INSTANCES  ADDRESS  PEEK  POKE
-	  LIST-ALL-REFERENCES  LIST-ALL-CATCHERS  LIST-ALL-BINDINGS
+	  LIST-ALL-REFERENCES  LIST-ALL-BLOCKS  LIST-ALL-CATCHERS  LIST-ALL-BINDINGS
 	  LIST-ALL-SPECIAL-BINDINGS  LIST-ALL-CLASSES))
 
   (export '*threads*)
diff --git a/lisp/l/exports.l b/lisp/l/exports.l
index ef5a29800..fa6c88c2a 100644
--- a/lisp/l/exports.l
+++ b/lisp/l/exports.l
@@ -170,7 +170,7 @@
 	  ALLOC  NEWSTACK  RECLAIM  RECLAIM-TREE
 	  OBJECT-SIZE  MEMORY-REPORT  CLEAR-MEMORY-REPORT
 	  ROOM  LIST-ALL-CHUNKS  LIST-ALL-INSTANCES  ADDRESS  PEEK  POKE
-	  LIST-ALL-REFERENCES  LIST-ALL-CATCHERS  LIST-ALL-BINDINGS
+	  LIST-ALL-REFERENCES  LIST-ALL-BLOCKS  LIST-ALL-CATCHERS  LIST-ALL-BINDINGS
 	  LIST-ALL-SPECIAL-BINDINGS  LIST-ALL-CLASSES))