diff --git a/compiler/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt b/compiler/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
index 7a0856f35..399f326ee 100644
--- a/compiler/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
+++ b/compiler/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
@@ -966,7 +966,23 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
             }
         }
 
-        // TODO optimize if right is variable or mem-read to avoid use of ZP location
+        if(right is IdentifierReference) {
+            asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
+            asmgen.out("  cmp  ${asmgen.asmVariableName(right)} |  bne  $jumpIfFalseLabel")
+            return
+        }
+        var memread = right as? DirectMemoryRead
+        if(memread==null && right is TypecastExpression)
+            memread = right.expression as? DirectMemoryRead
+        if(memread!=null) {
+            val address = memread.addressExpression as? NumericLiteralValue
+            if(address!=null) {
+                asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
+                asmgen.out("  cmp  ${address.number.toHex()} |  bne  $jumpIfFalseLabel")
+                return
+            }
+        }
+
         asmgen.assignExpressionToVariable(right, "P8ZP_SCRATCH_B1", DataType.UBYTE, null)
         asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
         asmgen.out("  cmp  P8ZP_SCRATCH_B1 |  bne  $jumpIfFalseLabel")
@@ -998,7 +1014,23 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
             }
         }
 
-        // TODO optimize if right is variable or mem-read to avoid use of ZP location
+        if(right is IdentifierReference) {
+            asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
+            asmgen.out("  cmp  ${asmgen.asmVariableName(right)} |  beq  $jumpIfFalseLabel")
+            return
+        }
+        var memread = right as? DirectMemoryRead
+        if(memread==null && right is TypecastExpression)
+            memread = right.expression as? DirectMemoryRead
+        if(memread!=null) {
+            val address = memread.addressExpression as? NumericLiteralValue
+            if(address!=null) {
+                asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
+                asmgen.out("  cmp  ${address.number.toHex()} |  beq  $jumpIfFalseLabel")
+                return
+            }
+        }
+
         asmgen.assignExpressionToVariable(right, "P8ZP_SCRATCH_B1", DataType.UBYTE, null)
         asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
         asmgen.out("  cmp  P8ZP_SCRATCH_B1 |  beq  $jumpIfFalseLabel")
@@ -1032,7 +1064,17 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
             }
         }
 
-        // TODO optimize if right is variable or mem-read to avoid use of ZP location
+        if(right is IdentifierReference) {
+            asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
+            asmgen.out("""
+                cmp  ${asmgen.asmVariableName(right)}
+                bne  $jumpIfFalseLabel
+                cpy  ${asmgen.asmVariableName(right)}+1
+                bne  $jumpIfFalseLabel
+                """)
+            return
+        }
+
         asmgen.assignExpressionToVariable(right, "P8ZP_SCRATCH_W2", DataType.UWORD, null)
         asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
         asmgen.out("""
@@ -1072,7 +1114,17 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
             }
         }
 
-        // TODO optimize if right is variable or mem-read to avoid use of ZP location
+        if(right is IdentifierReference) {
+            asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
+            asmgen.out("""
+                cmp  ${asmgen.asmVariableName(right)}
+                bne  +
+                cpy  ${asmgen.asmVariableName(right)}+1
+                beq  $jumpIfFalseLabel
++""")
+            return
+        }
+
         asmgen.assignExpressionToVariable(right, "P8ZP_SCRATCH_W2", DataType.UWORD, null)
         asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
         asmgen.out("""
diff --git a/examples/test.p8 b/examples/test.p8
index a6809277b..24adf5a26 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -4,6 +4,49 @@
 main {
     sub start() {
 
+        word xx
+        word yy
+
+        ; all comparisons with constant values are already optimized.
+        ; but for variables (and memreads) we can optimize further (don't use temporary ZP location)
+
+        word value = 100
+
+        while xx==value {
+            yy++
+        }
+
+        while xx!=value {
+            yy++
+        }
+
+        do {
+            yy++
+        } until xx==value
+
+        do {
+            yy++
+        } until xx!=value
+
+        if xx==value
+            yy++
+
+        if xx!=value
+            yy++
+
+;        while xx>value {
+;            yy++
+;        }
+;        do {
+;            yy++
+;        } until xx>value
+;
+;        if xx>value
+;            yy++
+    }
+
+    sub start3() {
+
         byte xx
         byte yy
 
@@ -16,11 +59,15 @@ main {
             yy++
         }
 
+        while xx==@($2000) {
+            yy++
+        }
+
         while xx!=value {
             yy++
         }
 
-        while xx>value {
+        while xx!=@($2000) {
             yy++
         }
 
@@ -32,18 +79,21 @@ main {
             yy++
         } until xx!=value
 
-        do {
-            yy++
-        } until xx>value
-
         if xx==value
             yy++
 
         if xx!=value
             yy++
 
-        if xx>value
-            yy++
+;        while xx>value {
+;            yy++
+;        }
+;        do {
+;            yy++
+;        } until xx>value
+;
+;        if xx>value
+;            yy++
     }