diff --git a/src/main/scala/millfork/compiler/m6809/M6809ExpressionCompiler.scala b/src/main/scala/millfork/compiler/m6809/M6809ExpressionCompiler.scala
index 6311b9b8..da21d78c 100644
--- a/src/main/scala/millfork/compiler/m6809/M6809ExpressionCompiler.scala
+++ b/src/main/scala/millfork/compiler/m6809/M6809ExpressionCompiler.scala
@@ -80,10 +80,22 @@ object M6809ExpressionCompiler extends AbstractExpressionCompiler[MLine] {
     }
     env.eval(expr) match {
       case Some(c) =>
-        return target match {
+        return (target match {
           case MExpressionTarget.NOTHING => Nil
           case _ => List(MLine.immediate(toLd(target), c))
-        }
+        }) ++ (branches match {
+          case BranchIfTrue(l) if c.isProvablyNonZero => List(MLine(JMP, Absolute(false), Label(l).toAddress))
+          case BranchIfTrue(l) =>
+            // TODO: ??
+            if (target == MExpressionTarget.NOTHING) List(MLine.immediate(LDB, c), MLine.longBranch(BNE, l))
+            else  List(MLine.longBranch(BNE, l))
+          case BranchIfFalse(l) if c.isProvablyZero => List(MLine(JMP, Absolute(false), Label(l).toAddress))
+          case BranchIfFalse(l) =>
+            // TODO: ??
+            if (target == MExpressionTarget.NOTHING) List(MLine.immediate(LDB, c), MLine.longBranch(BEQ, l))
+            else  List(MLine.longBranch(BEQ, l))
+          case NoBranching => Nil
+        })
       case None =>
     }
     expr match {
diff --git a/src/main/scala/millfork/env/Constant.scala b/src/main/scala/millfork/env/Constant.scala
index b241934b..08408e59 100644
--- a/src/main/scala/millfork/env/Constant.scala
+++ b/src/main/scala/millfork/env/Constant.scala
@@ -28,6 +28,7 @@ sealed trait Constant {
 
   def isQuiteNegative: Boolean = false
   def isProvablyZero: Boolean = false
+  def isProvablyNonZero: Boolean = false
   def isProvably(value: Int): Boolean = false
   def isProvablyInRange(startInclusive: Int, endInclusive: Int): Boolean = false
   def isProvablyNonnegative: Boolean = false
@@ -183,6 +184,7 @@ case class AssertByte(c: Constant) extends Constant {
   override def isQuiteNegative: Boolean = c.isQuiteNegative
   override def isProvablyGreaterOrEqualThan(other: Constant): Boolean = c.isProvablyGreaterOrEqualThan(other)
   override def isProvablyZero: Boolean = c.isProvablyZero
+  override def isProvablyNonZero: Boolean = c.isProvablyNonZero
   override def isProvably(i: Int): Boolean = c.isProvably(i)
   override def isProvablyNonnegative: Boolean = c.isProvablyNonnegative
   override def isProvablyNegative(asType: Type): Boolean = c.isProvablyNegative(asType)
@@ -277,6 +279,7 @@ case class NumericConstant(value: Long, requiredSize: Int) extends Constant {
   })
   override def isProvablyInRange(startInclusive: Int, endInclusive: Int): Boolean = value >= startInclusive && value <= endInclusive
   override def isProvablyZero: Boolean = value == 0
+  override def isProvablyNonZero: Boolean = value.&(0x1L.<<(8 * requiredSize - 1)) != 0
   override def isProvably(i: Int): Boolean = value == i
   override def isProvablyNonnegative: Boolean = value >= 0
   override def isProvablyNegative(asType: Type): Boolean = {