diff --git a/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt b/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
index 5f5dc75b7..69bb694a8 100644
--- a/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
+++ b/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
@@ -390,12 +390,22 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
 
     private fun funcStrlen(fcall: IFunctionCall) {
         val name = asmgen.asmVariableName(fcall.args[0] as IdentifierReference)
-        asmgen.out("""
-            lda  #<$name
-            ldy  #>$name
-            jsr  prog8_lib.strlen
-            sta  P8ESTACK_LO,x
-            dex""")
+        val type = fcall.args[0].inferType(program)
+        when {
+            type.istype(DataType.STR) -> asmgen.out("""
+                lda  #<$name
+                ldy  #>$name
+                jsr  prog8_lib.strlen
+                sta  P8ESTACK_LO,x
+                dex""")
+            type.istype(DataType.UWORD) -> asmgen.out("""
+                lda  $name
+                ldy  $name+1
+                jsr  prog8_lib.strlen
+                sta  P8ESTACK_LO,x
+                dex""")
+            else -> throw AssemblyError("strlen requires str or uword arg")
+        }
     }
 
     private fun funcSwap(fcall: IFunctionCall) {
diff --git a/compiler/src/prog8/functions/BuiltinFunctions.kt b/compiler/src/prog8/functions/BuiltinFunctions.kt
index 0f238840d..0b48fa23e 100644
--- a/compiler/src/prog8/functions/BuiltinFunctions.kt
+++ b/compiler/src/prog8/functions/BuiltinFunctions.kt
@@ -285,9 +285,9 @@ private fun builtinStrlen(args: List<Expression>, position: Position, program: P
         return NumericLiteralValue.optimalInteger(argument.value.length, argument.position)
     val vardecl = (argument as IdentifierReference).targetVarDecl(program.namespace)
     if(vardecl!=null) {
-        if(vardecl.datatype!=DataType.STR)
+        if(vardecl.datatype!=DataType.STR && vardecl.datatype!=DataType.UWORD)
             throw SyntaxError("strlen must have string argument", position)
-        if(vardecl.autogeneratedDontRemove) {
+        if(vardecl.autogeneratedDontRemove && vardecl.value!=null) {
             return NumericLiteralValue.optimalInteger((vardecl.value as StringLiteralValue).value.length, argument.position)
         }
     }
diff --git a/examples/test.p8 b/examples/test.p8
index 879f5003e..8cb3761e0 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -8,10 +8,25 @@ main {
     sub start() {
 
         ; TODO fix multi- string concatenation:
-        txt.print("\nCommands are:\n"+
-            "buy   jump      inf     cash\n" +
-            "sell  teleport  market  hold\n" +
-            "fuel  galhyp    local   quit\n")
+;        txt.print("\nCommands are:\n"+
+;            "buy   jump      inf     cash\n" +
+;            "sell  teleport  market  hold\n" +
+;            "fuel  galhyp    local   quit\n")
+
+        str name = "irmen de jong"
+        uword strptr = &name
+
+
+        txt.print_ub(strlen("1234"))
+        txt.chrout('\n')
+        txt.print_ub(strlen(name))
+        txt.chrout('\n')
+        txt.print_uwhex(strptr, 1)
+        txt.chrout('\n')
+        txt.print(strptr)
+        txt.chrout('\n')
+        txt.print_ub(strlen(strptr))
+        txt.chrout('\n')
 
 
     }