diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/BuiltinFunctionsAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/BuiltinFunctionsAsmGen.kt
index 674309762..75f3fac3b 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/BuiltinFunctionsAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/BuiltinFunctionsAsmGen.kt
@@ -292,10 +292,10 @@ internal class BuiltinFunctionsAsmGen(private val program: PtProgram,
                 }
             }
             DataType.FLOAT -> {
+                asmgen.out("  jsr  floats.func_sqrt_into_FAC1")
                 if(resultToStack)
-                    throw AssemblyError("no support for sqrt float onto stack")
+                    assignAsmGen.assignFAC1float(AsmAssignTarget(TargetStorageKind.STACK, asmgen, DataType.FLOAT, scope, fcall.position))
                 else {
-                    asmgen.out("  jsr  floats.func_sqrt_into_FAC1")
                     assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, true, fcall.position, scope, asmgen))
                 }
             }
@@ -688,7 +688,10 @@ internal class BuiltinFunctionsAsmGen(private val program: PtProgram,
             when (dt) {
                 DataType.BYTE -> asmgen.out("  jsr  prog8_lib.abs_b_stack")
                 DataType.WORD -> asmgen.out("  jsr  prog8_lib.abs_w_stack")
-                else -> throw AssemblyError("no support for abs onto stack for this dt")
+                else -> {
+                    asmgen.out("  jsr  floats.func_abs_f_into_FAC1")
+                    assignAsmGen.assignFAC1float(AsmAssignTarget(TargetStorageKind.STACK, asmgen, DataType.FLOAT, scope, fcall.position))
+                }
             }
         } else {
             when (dt) {
diff --git a/compiler/test/codegeneration/TestVariousCodeGen.kt b/compiler/test/codegeneration/TestVariousCodeGen.kt
index baeb421e7..429d925ef 100644
--- a/compiler/test/codegeneration/TestVariousCodeGen.kt
+++ b/compiler/test/codegeneration/TestVariousCodeGen.kt
@@ -165,4 +165,17 @@ main {
         compileText(C64Target(), true, text, writeAssembly = true, useNewExprCode = true) shouldNotBe null
         // no newexpr for IR targets: compileText(VMTarget(), true, text, writeAssembly = true, useNewExprCode = true) shouldNotBe null
     }
+
+    test("builtin func in float expression") {
+        val src="""
+%import floats
+main {
+    sub start() {
+        float @shared fl =25.1
+        fl = abs(fl)+0.5
+        fl = sqrt(fl)+0.5
+    }
+}"""
+        compileText(C64Target(), false, src, writeAssembly = true) shouldNotBe null
+    }
 })
\ No newline at end of file
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 9459abc06..c2eeab403 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -1,8 +1,6 @@
 TODO
 ====
 
-- c64 fix diskio.diskname
-
 - fix undefined symbol error for     sub curdir() -> str {  return "todo" }
 - fix placeholder error for
     str result = "todo"  ,   sub curdir() -> str { return result }