diff --git a/pxtcompiler/emitter/backvm.ts b/pxtcompiler/emitter/backvm.ts
index 2b06e2ac4741..1df9c3a83fb7 100644
--- a/pxtcompiler/emitter/backvm.ts
+++ b/pxtcompiler/emitter/backvm.ts
@@ -340,7 +340,7 @@ _start_${name}:
         vmsource += "\n; The end.\n"
         bin.writeFile(BINARY_ASM, vmsource)
 
-        let res = assemble(opts.target, bin, vmsource)
+        let res = assemble(opts.target, bin, vmsource, cres)
 
         const srcmap = res.thumbFile.getSourceMap()
         const encodedSrcMap = encodeSourceMap(srcmap)
diff --git a/pxtcompiler/emitter/hexfile.ts b/pxtcompiler/emitter/hexfile.ts
index 333441581c39..d61990c349e9 100644
--- a/pxtcompiler/emitter/hexfile.ts
+++ b/pxtcompiler/emitter/hexfile.ts
@@ -1015,13 +1015,19 @@ ${hexfile.hexPrelude()}
     }
 
     let peepDbg = false
-    export function assemble(target: CompileTarget, bin: Binary, src: string) {
+    export function assemble(target: CompileTarget, bin: Binary, src: string, cres: CompileResult) {
         let b = mkProcessorFile(target)
         b.emit(src);
 
+        let settingsSizeDefault = cres.configData.find(ce => ce.name === "SETTINGS_SIZE_DEFL")
+        let settingsSize = cres.configData.find(ce => ce.name === "SETTINGS_SIZE")
+        let actualSettingsSize = settingsSize ? settingsSize.value : settingsSizeDefault ? settingsSizeDefault.value : 0
+
+        let flashUsableEnd = (target.flashUsableEnd ? target.flashUsableEnd : target.flashEnd) - actualSettingsSize
+
         src = `; Interface tables: ${bin.itFullEntries}/${bin.itEntries} (${Math.round(100 * bin.itFullEntries / bin.itEntries)}%)\n` +
             `; Virtual methods: ${bin.numVirtMethods} / ${bin.numMethods}\n` +
-            b.getSource(!peepDbg, bin.numStmts, target.flashEnd);
+            b.getSource(!peepDbg, bin.numStmts, flashUsableEnd);
 
         throwAssemblerErrors(b)
 
@@ -1127,7 +1133,7 @@ __flash_checksums:
         }
         const prefix = opts.extinfo.outputPrefix || ""
         bin.writeFile(prefix + pxtc.BINARY_ASM, src)
-        const res = assemble(opts.target, bin, src)
+        const res = assemble(opts.target, bin, src, cres)
         if (res.thumbFile.commPtr)
             bin.commSize = res.thumbFile.commPtr - hexfile.getCommBase()
         if (res.src)
diff --git a/pxtlib/emitter/assembler.ts b/pxtlib/emitter/assembler.ts
index 6d131354c851..6de59bc30670 100644
--- a/pxtlib/emitter/assembler.ts
+++ b/pxtlib/emitter/assembler.ts
@@ -1067,7 +1067,7 @@ namespace ts.pxtc.assembler {
             return r
         }
 
-        public getSource(clean: boolean, numStmts = 1, flashSize = 0) {
+        public getSource(clean: boolean, numStmts = 1, flashUsableEnd = 0) {
             let lenPrev = 0
             let size = (lbl: string) => {
                 let curr = this.labels[lbl] || lenPrev
@@ -1081,18 +1081,18 @@ namespace ts.pxtc.assembler {
             let lenVtables = size("_vtables_end")
             let lenLiterals = size("_literals_end")
             let lenAllCode = lenPrev
-            let totalSize = (lenTotal + this.baseOffset) & 0xffffff
+            let totalEnd = (lenTotal + this.baseOffset) & 0xffffff
 
-            if (flashSize && totalSize > flashSize) {
-                const e = new Error(lf("program too big by {0} bytes!", totalSize - flashSize));
+            if (flashUsableEnd && totalEnd > flashUsableEnd) {
+                const e = new Error(lf("program too big by {0} bytes!", totalEnd - flashUsableEnd));
                 (e as any).ksErrorCode = 9283;
                 throw e;
             }
 
-            flashSize = flashSize || 128 * 1024
+            flashUsableEnd = flashUsableEnd || 128 * 1024
             let totalInfo = lf("; total bytes: {0} ({1}% of {2}k flash with {3} free)",
-                totalSize, (100 * totalSize / flashSize).toFixed(1), (flashSize / 1024).toFixed(1),
-                flashSize - totalSize)
+                totalEnd, (100 * totalEnd / flashUsableEnd).toFixed(1), (flashUsableEnd / 1024).toFixed(1),
+                flashUsableEnd - totalEnd)
             let res =
                 // ARM-specific
                 lf("; generated code sizes (bytes): {0} (incl. {1} user, {2} helpers, {3} vtables, {4} lits); src size {5}\n",