diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
index 2ac1ea2..43a4b7f 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
@@ -6002,6 +6002,11 @@ class BytecodeCompiler(
 
         try {
         val needsBreakFlag = stmt.canBreak || stmt.elseStatement != null
+        val realWidenSlots = collectLoopRealWidenSlots(stmt.body)
+        val hasRealWiden = realWidenSlots.isNotEmpty()
+        if (hasRealWiden) {
+            applySlotTypes(realWidenSlots, SlotType.REAL)
+        }
         val breakFlagSlot = allocSlot()
         if (range == null && rangeRef == null && typedRangeLocal == null) {
             val sourceValue = compileStatementValueOrFallback(stmt.source) ?: return null
@@ -6075,12 +6080,18 @@ class BytecodeCompiler(
                 )
             )
             val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
+            if (hasRealWiden) {
+                applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
+            }
             loopStack.removeLast()
             if (wantResult) {
                 val bodyObj = ensureObjSlot(bodyValue)
                 builder.emit(Opcode.MOVE_OBJ, bodyObj.slot, resultSlot!!)
             }
             builder.mark(continueLabel)
+            if (hasRealWiden) {
+                emitLoopRealCoercions(realWidenSlots)
+            }
             builder.emit(Opcode.JMP, listOf(CmdBuilder.Operand.LabelRef(loopLabel)))
 
             builder.mark(endLabel)
@@ -6188,6 +6199,9 @@ class BytecodeCompiler(
                     )
                 )
                 val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
+                if (hasRealWiden) {
+                    applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
+                }
                 loopStack.removeLast()
                 if (wantResult) {
                     val bodyObj = ensureObjSlot(bodyValue)
@@ -6195,6 +6209,9 @@ class BytecodeCompiler(
                 }
                 builder.mark(continueLabel)
                 builder.emit(Opcode.INC_INT, iSlot)
+                if (hasRealWiden) {
+                    emitLoopRealCoercions(realWidenSlots)
+                }
                 builder.emit(Opcode.JMP, listOf(CmdBuilder.Operand.LabelRef(loopLabel)))
 
                 builder.mark(endLabel)
@@ -6265,6 +6282,9 @@ class BytecodeCompiler(
             )
         )
         val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
+        if (hasRealWiden) {
+            applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
+        }
         loopStack.removeLast()
         if (wantResult) {
             val bodyObj = ensureObjSlot(bodyValue)
@@ -6272,6 +6292,9 @@ class BytecodeCompiler(
         }
         builder.mark(continueLabel)
         builder.emit(Opcode.INC_INT, iSlot)
+        if (hasRealWiden) {
+            emitLoopRealCoercions(realWidenSlots)
+        }
         builder.emit(Opcode.JMP, listOf(CmdBuilder.Operand.LabelRef(loopLabel)))
 
         builder.mark(endLabel)
@@ -6331,6 +6354,9 @@ class BytecodeCompiler(
             )
         )
         val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
+        if (hasRealWiden) {
+            applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
+        }
         loopStack.removeLast()
         if (wantResult) {
             val bodyObj = ensureObjSlot(bodyValue)
diff --git a/lynglib/src/commonTest/kotlin/ScriptTest.kt b/lynglib/src/commonTest/kotlin/ScriptTest.kt
index 187c223..c1b5ab6 100644
--- a/lynglib/src/commonTest/kotlin/ScriptTest.kt
+++ b/lynglib/src/commonTest/kotlin/ScriptTest.kt
@@ -1258,6 +1258,28 @@ class ScriptTest {
         )
     }
 
+    @Test
+    fun testForLoopRealWidenDisasm() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun widenFor() {
+                var acc = 0
+                for(i in 0..3) {
+                    if (i == 1) acc = 0.5
+                }
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("widenFor")
+        println("[DEBUG_LOG] widenFor disasm:\n$disasm")
+        val incIndex = disasm.indexOf("INC_INT")
+        assertTrue(incIndex >= 0, "expected INC_INT in for-loop disasm")
+        val convIndex = disasm.indexOf("INT_TO_REAL")
+        assertTrue(convIndex >= 0, "expected INT_TO_REAL in for-loop disasm")
+        assertTrue(convIndex > incIndex, "INT_TO_REAL should appear after INC_INT")
+    }
+
     @Test
     fun testIntClosedRangeInclusive() = runTest {
         eval(
diff --git a/notes/nested_range_baseline.md b/notes/nested_range_baseline.md
new file mode 100644
index 0000000..ea233d6
--- /dev/null
+++ b/notes/nested_range_baseline.md
@@ -0,0 +1,9 @@
+# Nested Range Benchmark Baseline
+
+Date: 2026-02-16
+
+Command:
+`BENCHMARKS=true timeout 20s ./gradlew :lynglib:jvmTest --tests NestedRangeBenchmarkTest --rerun-tasks`
+
+Result:
+- nested-happy elapsed=56 ms