diff --git a/compiler/src/prog8/ast/expressions/AstExpressions.kt b/compiler/src/prog8/ast/expressions/AstExpressions.kt
index d89de6043..857a0447c 100644
--- a/compiler/src/prog8/ast/expressions/AstExpressions.kt
+++ b/compiler/src/prog8/ast/expressions/AstExpressions.kt
@@ -302,7 +302,7 @@ class NumericLiteralValue(val type: DataType,    // only numerical types allowed
         }
     }
 
-    val asBooleanValue: Boolean = number!=0
+    val asBooleanValue: Boolean = number.toDouble() != 0.0
 
     override fun linkParents(parent: Node) {
         this.parent = parent
diff --git a/compiler/src/prog8/optimizer/StatementOptimizer.kt b/compiler/src/prog8/optimizer/StatementOptimizer.kt
index 21290ff5d..b1785b831 100644
--- a/compiler/src/prog8/optimizer/StatementOptimizer.kt
+++ b/compiler/src/prog8/optimizer/StatementOptimizer.kt
@@ -310,19 +310,20 @@ internal class StatementOptimizer(private val program: Program) : IAstModifyingV
         if(constvalue!=null) {
             return if(constvalue.asBooleanValue){
                 // always true -> print a warning, and optimize into body + jump (if there are no continue and break statements)
-                printWarning("condition is always true", whileLoop.position)  // TODO don't warn this if the condition is just the single value 'true'
+                printWarning("condition is always true", whileLoop.condition.position)
                 if(hasContinueOrBreak(whileLoop.body))
                     return whileLoop
-                val label = Label("_prog8_back", whileLoop.condition.position)
+                val backLabelName = "_prog8_back${whileLoop.position.line}"
+                val label = Label(backLabelName, whileLoop.condition.position)
                 whileLoop.body.statements.add(0, label)
                 whileLoop.body.statements.add(Jump(null,
-                        IdentifierReference(listOf("_prog8_back"), whileLoop.condition.position),
+                        IdentifierReference(listOf(backLabelName), whileLoop.condition.position),
                         null, whileLoop.condition.position))
                 optimizationsDone++
                 return whileLoop.body
             } else {
                 // always false -> ditch whole statement
-                printWarning("condition is always false", whileLoop.position)
+                printWarning("condition is always false", whileLoop.condition.position)
                 optimizationsDone++
                 NopStatement.insteadOf(whileLoop)
             }
@@ -336,7 +337,7 @@ internal class StatementOptimizer(private val program: Program) : IAstModifyingV
         if(constvalue!=null) {
             return if(constvalue.asBooleanValue){
                 // always true -> keep only the statement block (if there are no continue and break statements)
-                printWarning("condition is always true", repeatLoop.position)  // TODO don't warn this if the condition is just the single value 'true'
+                printWarning("condition is always true", repeatLoop.untilCondition.position)
                 if(hasContinueOrBreak(repeatLoop.body))
                     repeatLoop
                 else {
@@ -345,13 +346,14 @@ internal class StatementOptimizer(private val program: Program) : IAstModifyingV
                 }
             } else {
                 // always false -> print a warning, and optimize into body + jump (if there are no continue and break statements)
-                printWarning("condition is always false", repeatLoop.position)
+                printWarning("condition is always false", repeatLoop.untilCondition.position)
                 if(hasContinueOrBreak(repeatLoop.body))
                     return repeatLoop
-                val label = Label("__back", repeatLoop.untilCondition.position)
+                val backLabelName = "_prog8_back${repeatLoop.position.line}"
+                val label = Label(backLabelName, repeatLoop.untilCondition.position)
                 repeatLoop.body.statements.add(0, label)
                 repeatLoop.body.statements.add(Jump(null,
-                        IdentifierReference(listOf("__back"), repeatLoop.untilCondition.position),
+                        IdentifierReference(listOf(backLabelName), repeatLoop.untilCondition.position),
                         null, repeatLoop.untilCondition.position))
                 optimizationsDone++
                 return repeatLoop.body
diff --git a/docs/docs.iml b/docs/docs.iml
index 436bded7a..9918696de 100644
--- a/docs/docs.iml
+++ b/docs/docs.iml
@@ -5,7 +5,7 @@
     <content url="file://$MODULE_DIR$">
       <excludeFolder url="file://$MODULE_DIR$/build" />
     </content>
-    <orderEntry type="jdk" jdkName="Python 3.7 (py3)" jdkType="Python SDK" />
+    <orderEntry type="jdk" jdkName="Python 3.8 virtualenv" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
 </module>
\ No newline at end of file
diff --git a/docs/source/programming.rst b/docs/source/programming.rst
index 1424830b0..4668b1027 100644
--- a/docs/source/programming.rst
+++ b/docs/source/programming.rst
@@ -282,10 +282,10 @@ a string literal a given number of times using '*'::
 
 
 .. caution::
-    It's probably best that you don't change strings after they're created.
+    Avoid changing strings after they've been created.
     This is because if your program exits and is restarted (without loading it again),
-    it will then operate on the changed strings instead of the original ones.
-    The same is true for arrays by the way.
+    it will then start working with the changed strings instead of the original ones.
+    The same is true for arrays.
 
 
 Structs
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 5cf48c9c7..b9a98f2de 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -2,6 +2,11 @@
 TODO
 ====
 
+- @"zzz"  screencode encoded strings  + add this to docs too
+- add 'void' keyword to explicitly ignore subroutine return values
+- allow:  for bb in [1,2,3]  + docs?
+
+
 Memory Block Operations integrated in language?
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^