diff --git a/src/worker/workermain.ts b/src/worker/workermain.ts
index 49e6e475..f8e6bf0b 100644
--- a/src/worker/workermain.ts
+++ b/src/worker/workermain.ts
@@ -1253,6 +1253,9 @@ function fixParamsWithDefines(path:string, params){
         } else if (ident == 'LIBARGS' && value) {
           params.libargs = value.split(',').filter((s) => { return s!=''; });
           console.log('Using libargs', params.libargs);
+        } else if (ident == 'CC65_FLAGS' && value) {
+          params.extra_compiler_args = value.split(',').filter((s) => { return s!=''; });
+          console.log('Using compiler flags', params.extra_compiler_args);
         }
       }
     }
@@ -1292,9 +1295,7 @@ function compileCC65(step:BuildStep) {
     setupFS(FS, '65-'+getRootBasePlatform(step.platform));
     populateFiles(step, FS);
     fixParamsWithDefines(step.path, params);
-    var args = ['-T', '-g',
-      '-Oirs', // don't inline CodeSizeFactor 200? (no -Oi)
-      '-Cl', // static locals
+    var args = [
       '-I', '/share/include',
       '-I', '.',
       "-D", "__8BITWORKSHOP__",
@@ -1305,6 +1306,8 @@ function compileCC65(step:BuildStep) {
     if (step.mainfile) {
       args.unshift.apply(args, ["-D", "__MAIN__"]);
     }
+    var customArgs = params.extra_compiler_args || ['-T', '-g', '-Oirs', '-Cl'];
+    args = args.concat(customArgs, args);
     args.push(step.path);
     //console.log(args);
     execMain(step, CC65, args);
diff --git a/test/cli/testworker.js b/test/cli/testworker.js
index 66c1924b..49992b63 100644
--- a/test/cli/testworker.js
+++ b/test/cli/testworker.js
@@ -260,5 +260,8 @@ describe('Worker', function() {
     };
     doBuild(msgs, done2, 205, 0, 0);
   });
+  it('should compile CC65 flags', function(done) {
+    compile('cc65', '#define CC65_FLAGS -O1,-j\nint main() {\nint x=1;\nreturn x+2;\n}', 'apple2', done, 14697, 5);
+  });
 
 });