diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
index 069fdb510..1cccb3890 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
@@ -324,18 +324,24 @@ internal class AssignmentAsmGen(private val program: Program,
     }
 
     internal fun assignPrefixedExpressionToArrayElt(assign: AsmAssignment) {
-        // array[x] = -value   ... use a tempvar then store that back into the array.
         require(assign.source.expression is PrefixExpression)
-        val tempvar = asmgen.getTempVarName(assign.target.datatype).joinToString(".")
-        val assignToTempvar = AsmAssignment(assign.source,
-            AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, assign.target.datatype, assign.target.scope, variableAsmName=tempvar, origAstTarget = assign.target.origAstTarget),
-            false, program.memsizer, assign.position)
-        asmgen.translateNormalAssignment(assignToTempvar)
-        when(assign.target.datatype) {
-            in ByteDatatypes -> assignVariableByte(assign.target, tempvar)
-            in WordDatatypes -> assignVariableWord(assign.target, tempvar)
-            DataType.FLOAT -> assignVariableFloat(assign.target, tempvar)
-            else -> throw AssemblyError("weird dt")
+        if(assign.source.datatype==DataType.FLOAT) {
+            // floatarray[x] = -value   ... just use FAC1 to calculate the expression into and then store that back into the array.
+            assignExpressionToRegister(assign.source.expression, RegisterOrPair.FAC1, true)
+            assignFAC1float(assign.target)
+        } else {
+            // array[x] = -value   ... use a tempvar then store that back into the array.
+            val tempvar = asmgen.getTempVarName(assign.target.datatype).joinToString(".")
+            val assignToTempvar = AsmAssignment(assign.source,
+                AsmAssignTarget(TargetStorageKind.VARIABLE, asmgen, assign.target.datatype, assign.target.scope, variableAsmName=tempvar, origAstTarget = assign.target.origAstTarget),
+                false, program.memsizer, assign.position)
+            asmgen.translateNormalAssignment(assignToTempvar)
+            when(assign.target.datatype) {
+                in ByteDatatypes -> assignVariableByte(assign.target, tempvar)
+                in WordDatatypes -> assignVariableWord(assign.target, tempvar)
+                DataType.FLOAT -> assignVariableFloat(assign.target, tempvar)
+                else -> throw AssemblyError("weird dt")
+            }
         }
     }
 
diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AugmentableAssignmentAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AugmentableAssignmentAsmGen.kt
index 4853e5d87..57679696b 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AugmentableAssignmentAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AugmentableAssignmentAsmGen.kt
@@ -1965,6 +1965,13 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
             }
             DataType.FLOAT -> {
                 when (target.kind) {
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.FAC1 -> asmgen.out("  jsr  floats.NEGOP")
+                            RegisterOrPair.FAC2 -> asmgen.out("  jsr  floats.MOVFA |  jsr floats.NEGOP |  jsr  floats.MOVEF")
+                            else -> throw AssemblyError("invalid float register")
+                        }
+                    }
                     TargetStorageKind.VARIABLE -> {
                         // simply flip the sign bit in the float
                         asmgen.out("""
@@ -1975,7 +1982,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                     }
                     TargetStorageKind.STACK -> TODO("no asm gen for float stack negate")
                     TargetStorageKind.ARRAY -> assignmentAsmGen.assignPrefixedExpressionToArrayElt(assign)
-                    else -> throw AssemblyError("weird target for float negation")
+                    else -> throw AssemblyError("weird target for in-place float negation")
                 }
             }
             else -> throw AssemblyError("negate of invalid type")
diff --git a/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt b/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
index 57dc67daf..6c44d5ce4 100644
--- a/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
+++ b/codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt
@@ -293,9 +293,9 @@ class StatementOptimizer(private val program: Program,
         val bexpr=assignment.value as? BinaryExpression
         if(bexpr!=null) {
             val rightCv = bexpr.right.constValue(program)?.number
-            if(bexpr.operator=="-" && rightCv==null) {
+            if(bexpr.operator=="-" && rightCv==null && targetIDt.isInteger) {
                 if(bexpr.right.isSimple && bexpr.right isSameAs assignment.target) {
-                    // X = value - X  -->  X = -X ; X += value  (to avoid need of stack-evaluation)
+                    // X = value - X  -->  X = -X ; X += value  (to avoid need of stack-evaluation, for integers)
                     val negation = PrefixExpression("-", bexpr.right.copy(), bexpr.position)
                     val addValue = Assignment(assignment.target.copy(), BinaryExpression(bexpr.right, "+", bexpr.left, bexpr.position), AssignmentOrigin.OPTIMIZER, assignment.position)
                     return listOf(
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 6626813e1..6cbfb7c9a 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -3,7 +3,6 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-- check StatementOptimizer "optimize binary expressions a bit": flt[1] = 3.0-flt[1]  beneficial or not? what about integer array?
 - ir: get rid of '_' label prefix?
 - fix expericodegen (ir code gen for regular cx16 target)
 
@@ -53,7 +52,7 @@ Libraries:
 - optimize several inner loops in gfx2 even further?
 - add modes 3 and perhaps even 2 to gfx2 (lores 16 color and 4 color)?
 - add a flood fill (span fill/scanline fill) routine to gfx2?
-- add a p
+- add a pget() to gfx2 to get the pixel color value
 
 
 Expressions:
diff --git a/examples/test.p8 b/examples/test.p8
index 99a0ac434..1ce3a2084 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -7,7 +7,7 @@ main {
 
   sub start() {
     flt[1] = 42.42
-    flt[1] = 3-flt[1]
+    flt[1] = -flt[1]
     floats.print_f(flt[1])
   }
 }