diff --git a/blk/104 b/blk/104
index 3ef1cfe..a671441 100644
--- a/blk/104
+++ b/blk/104
@@ -10,7 +10,7 @@ VARIABLE EDPOS
         2DUP SWAP I + C!
         DUP IF DROP C< THEN
     LOOP
+    2DROP
+    BLK!!
 ;
 
-
-
diff --git a/emul/Makefile b/emul/Makefile
index e47bc08..9a7104d 100644
--- a/emul/Makefile
+++ b/emul/Makefile
@@ -16,6 +16,7 @@ SLATEST = ../tools/slatest
 STRIPFC = ../tools/stripfc
 BIN2C = ../tools/bin2c
 BLKPACK = ../tools/blkpack
+BLKUNPACK = ../tools/blkunpack
 
 .PHONY: all
 all: $(TARGETS)
@@ -27,6 +28,7 @@ $(BLKPACK):
 $(STRIPFC): $(BLKPACK)
 $(SLATEST): $(BLKPACK)
 $(BIN2C): $(BLKPACK)
+$(BLKUNPACK): $(BLKPACK)
 
 # z80c.bin is not in the prerequisites because it's a bootstrap
 # binary that should be updated manually through make updatebootstrap.
@@ -77,6 +79,14 @@ emul.o: emul.c
 updatebootstrap: forth/stage2
 	cat $(BOOTSRCS) | ./forth/stage2 > ./forth/z80c.bin
 
+.PHONY: pack
+pack:
+	rm blkfs && $(MAKE) blkfs
+
+.PHONY: unpack
+unpack:
+	$(BLKUNPACK) ../blk < blkfs
+
 .PHONY: clean
 clean:
 	rm -f $(TARGETS) emul.o forth/*-bin.h forth/forth?.bin blkfs
diff --git a/forth/blk.fs b/forth/blk.fs
index e4fde66..7e9d610 100644
--- a/forth/blk.fs
+++ b/forth/blk.fs
@@ -7,26 +7,35 @@
 : BLK!* 2 BLKMEM+ ;
 ( Current blk pointer in ( )
 : BLK> 4 BLKMEM+ ;
-: BLK( 6 BLKMEM+ ;
+( Whether buffer is dirty )
+: BLKDTY 6 BLKMEM+ ;
+: BLK( 8 BLKMEM+ ;
 
 : BLK$
     H@ 0x57 RAM+ !
-    ( 1024 for the block, 6 for variables )
-    1030 ALLOT
+    ( 1024 for the block, 8 for variables )
+    1032 ALLOT
     ( LOAD detects end of block with ASCII EOT. This is why
       we write it there. EOT == 0x04 )
     4 C,
+    0 BLKDTY !
     -1 BLK> !
 ;
 
+( -- )
+: BLK!
+    BLK> @ BLK!* @ EXECUTE
+    0 BLKDTY !
+;
+
 ( n -- )
 : BLK@
     DUP BLK> @ = IF DROP EXIT THEN
+    BLKDTY @ IF BLK! THEN
     DUP BLK> ! BLK@* @ EXECUTE
 ;
 
-( -- )
-: BLK! BLK> @ BLK!* @ EXECUTE ;
+: BLK!! 1 BLKDTY ! ;
 
 : .2 DUP 10 < IF SPC THEN . ;
 
@@ -42,7 +51,10 @@
 : _
     (boot<)
     DUP 4 = IF
-        DROP
+        ( We drop our char, but also "a" from WORD: it won't
+          have the opportunity to balance PSP because we're
+          EXIT!ing. )
+        2DROP
         ( We're finished interpreting )
         EXIT!
     THEN
diff --git a/forth/core.fs b/forth/core.fs
index 129b912..5e05eb4 100644
--- a/forth/core.fs
+++ b/forth/core.fs
@@ -178,6 +178,7 @@
     DUP                 ( I I )
     R> DROP I 2- @     ( I I a )
     = UNTIL
+    DROP
 ;
 
 ( a -- a+1 c )
diff --git a/tools/blkunpack.c b/tools/blkunpack.c
index c252671..19fc271 100644
--- a/tools/blkunpack.c
+++ b/tools/blkunpack.c
@@ -26,7 +26,6 @@ int main(int argc, char *argv[])
         }
         if (c) {
             // not an empty block
-            printf("%s\n", fullpath);
             FILE *fp = fopen(fullpath, "w");
             for (int i=0; i<16; i++) {
                 int len = strlen(&buf[i*64]);