diff --git a/compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt b/compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt
index 2a4b30b58..27ca32e1a 100644
--- a/compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt
+++ b/compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt
@@ -1327,9 +1327,11 @@ $repeatLabel    lda  $counterVar
                 val sourcePath = stmt.definingModule().source // FIXME: %asmbinary inside non-library, non-filesystem module
                 val includedPath = sourcePath.resolveSibling(includedName)
 
-                val pathForAssembler = outputDir // 64tass needs the path *relative to the .asm file*
+                val pathForAssembler = outputDir // #54: 64tass needs the path *relative to the .asm file*
                     .absolute() // avoid IllegalArgumentExc due to non-absolute path .relativize(absolute path)
                     .relativize(includedPath)
+                    .normalize() // avoid assembler warnings (-Wportable; only some, not all)
+                    .toString().replace('\\', '/')
                 out("  .binary \"$pathForAssembler\" $offset $length")
             }
             "%breakpoint" -> {
diff --git a/compiler/test/TestCompilerOnImportsAndIncludes.kt b/compiler/test/TestCompilerOnImportsAndIncludes.kt
index e67600783..d166f92d3 100644
--- a/compiler/test/TestCompilerOnImportsAndIncludes.kt
+++ b/compiler/test/TestCompilerOnImportsAndIncludes.kt
@@ -117,7 +117,7 @@ class TestCompilerOnImportsAndIncludes {
             dynamicTest(displayName) {
                 assumeReadableFile(p8Path)
                 assumeReadableFile(binPath)
-                assertNotEquals( // the bug we're testing for (#??) was hidden if outputDir == workinDir
+                assertNotEquals( // the bug we're testing for (#54) was hidden if outputDir == workinDir
                     workingDir.normalize().toAbsolutePath(),
                     outputDir.normalize().toAbsolutePath(),
                     "sanity check: workingDir and outputDir should not be the same folder")