diff --git a/compiler/src/prog8/compiler/astprocessing/VerifyFunctionArgTypes.kt b/compiler/src/prog8/compiler/astprocessing/VerifyFunctionArgTypes.kt
index 011306334..2fa6a9f12 100644
--- a/compiler/src/prog8/compiler/astprocessing/VerifyFunctionArgTypes.kt
+++ b/compiler/src/prog8/compiler/astprocessing/VerifyFunctionArgTypes.kt
@@ -5,6 +5,7 @@ import prog8.ast.Program
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
 import prog8.ast.walk.IAstVisitor
+import prog8.code.core.ByteDatatypes
 import prog8.code.core.DataType
 import prog8.code.core.IErrorReporter
 import prog8.code.core.Position
@@ -82,7 +83,9 @@ internal class VerifyFunctionArgTypes(val program: Program, val errors: IErrorRe
                 if(mismatch>=0) {
                     val actual = argtypes[mismatch]
                     val expected = consideredParamTypes[mismatch]
-                    return if(expected==DataType.BOOL && actual==DataType.UBYTE && call.args[mismatch].constValue(program)?.number in setOf(0.0, 1.0))
+                    return if(actual==DataType.BOOL && expected in ByteDatatypes)
+                        null  // a bool is just 1 or 0.
+                    else if(expected==DataType.BOOL && actual==DataType.UBYTE && call.args[mismatch].constValue(program)?.number in setOf(0.0, 1.0))
                         null  // specifying a 1 or 0 as a BOOL is okay
                     else
                         Pair("argument ${mismatch + 1} type mismatch, was: $actual expected: $expected", call.args[mismatch].position)
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 4f240ac97..98bdc1f56 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -3,7 +3,6 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-- fix error when passing boolean expression as ubyte param to a functioncall
 - fix expericodegen crashes from missing functions from virtual/prog8_lib.p8
 
 ...
diff --git a/examples/test.p8 b/examples/test.p8
index 12aabae94..226ccc08d 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -1,21 +1,24 @@
 %import textio
+%import string
 %zeropage basicsafe
 
 main {
 
     str name1 = "abc"
     str name2 = "irmen"
-    ubyte v1
-    ubyte v2
-
-    sub func(ubyte value) {
-        value++
-    }
+    ubyte[] arr1 = [11,22,33]
+    uword[] arr2 = [1111,2222,3333]
 
   sub start() {
-    func(v1==v2)
-    func(v1>v2)
-    func(name1 == name2)
-    func(name1 > name2)
+    ubyte @shared xx
+    ubyte value = 33
+    uword value2 = 3333
+    txt.print_ub(value in name1)
+    txt.print_ub('c' in name1)
+    txt.print_ub(name1 == name2)
+    txt.print_ub(name1 < name2)
+    txt.print_ub(value in arr1)
+    txt.print_ub(value2 in arr2)
+
   }
 }
diff --git a/virtualmachine/src/prog8/vm/SysCalls.kt b/virtualmachine/src/prog8/vm/SysCalls.kt
index 34c5a88ec..03b85e09d 100644
--- a/virtualmachine/src/prog8/vm/SysCalls.kt
+++ b/virtualmachine/src/prog8/vm/SysCalls.kt
@@ -284,7 +284,12 @@ object SysCalls {
                 val first = vm.memory.getString(firstAddr.toInt())
                 val second = vm.memory.getString(secondAddr.toInt())
                 val comparison = first.compareTo(second)
-                vm.registers.setSB(0, comparison.toByte())
+                if(comparison==0)
+                    vm.registers.setSB(0, 0)
+                else if(comparison<0)
+                    vm.registers.setSB(0, -1)
+                else
+                    vm.registers.setSB(0, 1)
             }
             Syscall.RNDFSEED -> {
                 val seed1 = vm.registers.getUB(0)