diff --git a/README.md b/README.md
index 9008911..a43108e 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,10 @@ Here are all currently known implementations of LTTB:
 
 * [Jim Tcl port](./lttb.tcl) (284 SLOC)
 
+## Test suite
+
+LTTB also ships a [test suite](test.bas) source code file to verify implementation correctness. Every non-empty line between the start and the end should end with `OK`.
+
 ## FAQ
 
 Please read the [manual](lttb-manual.md) first, your question is most likely covered there. If not, here are some more questions and answers.
diff --git a/lttb-impl-notes.md b/lttb-impl-notes.md
index 8fdf447..b0c5b49 100644
--- a/lttb-impl-notes.md
+++ b/lttb-impl-notes.md
@@ -218,7 +218,7 @@ Value and string printing routine. Accepts `STMT` string as a parameter.
 Run the program currently loaded into the working memory.
 
 1. Set `IP = 1`.
-2. If `PROGMEM[IP]` exists and is not empty, execute `PROGEXEC(PROGMEM[IP])`.
+2. If `PROGMEM[IP]` exists, is not empty and does not start with the string `REM`, execute `PROGEXEC(PROGMEM[IP])`.
 3. Increment `IP` by 1.
 4. If `IP > 0` and `IP < 32768`, go to step 2.
 
@@ -279,3 +279,5 @@ Program saving routine into external storage media. The provided algorithm works
 ## Closing notes
 
 The set of algorithms in this document should be enough to create a complete and functional LTTB interpreter in any modern programming language. If you have any corrections or optimizations regarding the algorithms, feel free to create an issue in this repository.
+
+In order to verify implementation correctness, you can use the code inside [test.bas](test.bas) shipped in this repository.
diff --git a/lttb.tcl b/lttb.tcl
index 35ef317..7b9e045 100755
--- a/lttb.tcl
+++ b/lttb.tcl
@@ -256,7 +256,7 @@ proc int_RUN {} {
   global progmem ip
   set ip 1
   while {$ip > 0 && $ip < 32768} {
-    if {[dict exists $progmem $ip]} {lttb_exec $progmem($ip)}
+    if {[dict exists $progmem $ip] && [string first REM $progmem($ip)] != 0} {lttb_exec $progmem($ip)}
     incr ip
   }
 }
diff --git a/test.bas b/test.bas
new file mode 100644
index 0000000..ea7235a
--- /dev/null
+++ b/test.bas
@@ -0,0 +1,65 @@
+5   rem This is a comment and should never be executed
+10  print "Luxferre's Truly Tiny BASIC test suite"
+15  print ""
+20  print "All lines should end with OK to pass"
+30  print "Let's go..."
+35  print ""
+40  print "Nested IF and A-I zero init: ";
+50  if a=0 if b=0 if c=0 if d=0 if e=0 if g=0 if h=0 if i=0 print "OK"
+55  print ""
+60  print "Nested IF and J-Q zero init: ";
+70  if j=0 if k=0 if l=0 if m=0 if n=0 if o=0 if p=0 if q=0 print "OK"
+75  print ""
+80  print "Nested IF and R-Y zero init: ";
+90  if r=0 if s=0 if t=0 if u=0 if v=0 if w=0 if x=0 if y=0 print "OK"
+95  print ""
+100 print "Z zero init: ";
+110 if z=0 print "OK"
+120 print ""
+130 print "Precedence: ";
+140 if 2 + 2 * 2 - 3 / 3 = 5 print "OK"
+150 print "" 
+160 print "Left assoc and full THEN form: ";
+170 if 63 / 8 * 8 = 56 then print "OK"
+180 print ""
+190 print "Parentheses: ";
+200 if 5 * (2+3) * (4 + 1) = 125 print "OK"
+210 print ""
+220 print "Int pos wrap: ";
+230 if 32767 + 1 = -32768 print "OK"
+240 print ""
+250 print "Int neg wrap: ";
+260 if -32768 - 1 = 32767 print "OK"
+270 print ""
+280 print "int mod wrap: ";
+290 if 32767 + 65535 = 32766 print "OK"
+300 print ""
+310 print "This should display 108 after a space: ";12*9;" -> OK"
+315 print ""
+320 print "This should display 56 after a tab: ", 63/8*8 ; " -> OK"
+325 print ""
+330 print "GOTO: ";
+340 goto 3 * 300
+350 print ""
+360 print "GOSUB: ";
+370 GOSUB 2 + 918
+380 print "OK"
+390 print ""
+400 print "RND: ";
+410 x = rnd(100) + rnd(100) + rnd(100) + rnd(100) + rnd(100) + rnd(100)
+420 if x < 600 if rnd(100) <> x/6 print "OK"
+430 print ""
+440 print "Indirect line rewriting in if/then form: ";
+450 if x > -1 then 950 print "OK"
+460 gosub 950
+470 print ""
+480 print "Test end, thank you!"
+490 end
+890 print "This line should never be printed"
+900 print "OK"
+910 goto 350
+920 print "OK"
+930 print "RETURN: ";
+940 return
+950 print "NOT OK"
+960 return