diff --git a/sjsonnet/src/sjsonnet/Evaluator.scala b/sjsonnet/src/sjsonnet/Evaluator.scala
index bb7632df..cc54e6ad 100644
--- a/sjsonnet/src/sjsonnet/Evaluator.scala
+++ b/sjsonnet/src/sjsonnet/Evaluator.scala
@@ -240,7 +240,7 @@ class Evaluator(
   @inline private def tryInlineArith(op: Int, ld: Double, rd: Double, pos: Position): Val =
     (op: @switch) match {
       case Expr.BinaryOp.OP_* =>
-        val r = ld * rd; if (r.isInfinite) null else Val.cachedNum(pos, r)
+        val r = ld * rd; if (r.isNaN || r.isInfinite) null else Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_/ =>
         if (rd == 0) null
         else { val r = ld / rd; if (r.isNaN || r.isInfinite) null else Val.cachedNum(pos, r) }
@@ -248,9 +248,9 @@ class Evaluator(
         if (rd == 0) null
         else { val r = ld % rd; if (r.isNaN) null else Val.cachedNum(pos, r) }
       case Expr.BinaryOp.OP_+ =>
-        val r = ld + rd; if (r.isInfinite) null else Val.cachedNum(pos, r)
+        val r = ld + rd; if (r.isNaN || r.isInfinite) null else Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_- =>
-        val r = ld - rd; if (r.isInfinite) null else Val.cachedNum(pos, r)
+        val r = ld - rd; if (r.isNaN || r.isInfinite) null else Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_<< =>
         val ll = ld.toLong; val rl = rd.toLong
         if (ll.toDouble != ld || rl.toDouble != rd) null // not safe integers
@@ -706,23 +706,32 @@ class Evaluator(
     val ld = ln.asDouble
     val rd = rn.asDouble
     (op: @switch) match {
-      case Expr.BinaryOp.OP_+ => Val.cachedNum(pos, ld + rd)
+      case Expr.BinaryOp.OP_+ =>
+        val r = ld + rd
+        if (r.isNaN) Error.fail("not a number", pos)
+        if (r.isInfinite) Error.fail("overflow", pos)
+        Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_- =>
         val r = ld - rd
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos)
         Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_* =>
         val r = ld * rd
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos)
         Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_/ =>
         if (rd == 0) Error.fail("Division by zero.", pos)
         val r = ld / rd
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos)
         Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_% =>
         if (rd == 0) Error.fail("Division by zero.", pos)
-        Val.cachedNum(pos, ld % rd)
+        val r = ld % rd
+        if (r.isNaN) Error.fail("not a number", pos)
+        Val.cachedNum(pos, r)
       // Use position-free static singletons for boolean results — this method is only called
       // from comprehension fast paths where position info on boolean results is unnecessary.
       // Avoids 1 object allocation per comparison in inner loops (significant for 1M+ iterations).
@@ -857,23 +866,28 @@ class Evaluator(
     (e.op: @switch) match {
       case Expr.BinaryOp.OP_* =>
         val r = visitExprAsDouble(e.lhs) * visitExprAsDouble(e.rhs)
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos); r
       case Expr.BinaryOp.OP_/ =>
         val l = visitExprAsDouble(e.lhs)
         val r = visitExprAsDouble(e.rhs)
         if (r == 0) Error.fail("Division by zero.", pos)
         val result = l / r
+        if (result.isNaN) Error.fail("not a number", pos)
         if (result.isInfinite) Error.fail("overflow", pos); result
       case Expr.BinaryOp.OP_% =>
         val l = visitExprAsDouble(e.lhs)
         val r = visitExprAsDouble(e.rhs)
         if (r == 0) Error.fail("Division by zero.", pos)
-        l % r
+        val result = l % r
+        if (result.isNaN) Error.fail("not a number", pos); result
       case Expr.BinaryOp.OP_+ =>
         val r = visitExprAsDouble(e.lhs) + visitExprAsDouble(e.rhs)
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos); r
       case Expr.BinaryOp.OP_- =>
         val r = visitExprAsDouble(e.lhs) - visitExprAsDouble(e.rhs)
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos); r
       case Expr.BinaryOp.OP_<< =>
         val ll = visitExprAsDouble(e.lhs).toSafeLong(pos)
@@ -1334,10 +1348,12 @@ class Evaluator(
       // Pure numeric fast path: avoid intermediate Val.Num allocation
       case Expr.BinaryOp.OP_* =>
         val r = visitExprAsDouble(e.lhs) * visitExprAsDouble(e.rhs)
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos)
         Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_- =>
         val r = visitExprAsDouble(e.lhs) - visitExprAsDouble(e.rhs)
+        if (r.isNaN) Error.fail("not a number", pos)
         if (r.isInfinite) Error.fail("overflow", pos)
         Val.cachedNum(pos, r)
       case Expr.BinaryOp.OP_/ =>
@@ -1370,9 +1386,13 @@ class Evaluator(
         val l = visitExpr(e.lhs)
         val r = visitExpr(e.rhs)
         (l, r) match {
-          case (Val.Num(_, l), Val.Num(_, r)) => Val.cachedNum(pos, l + r)
-          case (l: Val.Str, r: Val.Str)       => Val.Str.concat(pos, l, r)
-          case (n: Val.Num, r: Val.Str)       =>
+          case (Val.Num(_, l), Val.Num(_, r)) =>
+            val result = l + r
+            if (result.isNaN) Error.fail("not a number", pos)
+            if (result.isInfinite) Error.fail("overflow", pos)
+            Val.cachedNum(pos, result)
+          case (l: Val.Str, r: Val.Str) => Val.Str.concat(pos, l, r)
+          case (n: Val.Num, r: Val.Str) =>
             Val.Str.concat(pos, Val.Str(pos, RenderUtils.renderDouble(n.asDouble)), r)
           case (l: Val.Str, n: Val.Num) =>
             Val.Str.concat(pos, l, Val.Str(pos, RenderUtils.renderDouble(n.asDouble)))
diff --git a/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet b/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet
new file mode 100644
index 00000000..bf389610
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet
@@ -0,0 +1,5 @@
+// Test that normal arithmetic operations still work correctly.
+assert 1 + 2 == 3;
+assert 3 * 4 == 12;
+assert 10 - 3 == 7;
+true
diff --git a/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet.golden
new file mode 100644
index 00000000..27ba77dd
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/arithmetic_normal_operations.jsonnet.golden
@@ -0,0 +1 @@
+true
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet
new file mode 100644
index 00000000..87214820
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet
@@ -0,0 +1,2 @@
+// Test that addition overflow (Infinity) errors instead of silently propagating.
+1e308 + 1e308
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet.golden
new file mode 100644
index 00000000..d6cfd626
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_addition.jsonnet.golden
@@ -0,0 +1,2 @@
+sjsonnet.Error: overflow
+    at [<root>].(error.arithmetic_overflow_addition.jsonnet:2:7)
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet
new file mode 100644
index 00000000..0ee10de9
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet
@@ -0,0 +1,2 @@
+// Test that multiplication overflow (Infinity) errors instead of silently propagating.
+1e308 * 1e308
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet.golden
new file mode 100644
index 00000000..47400074
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_multiplication.jsonnet.golden
@@ -0,0 +1,2 @@
+sjsonnet.Error: overflow
+    at [<root>].(error.arithmetic_overflow_multiplication.jsonnet:2:7)
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet
new file mode 100644
index 00000000..55906eda
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet
@@ -0,0 +1,2 @@
+// Test that subtraction overflow (Infinity) errors instead of silently propagating.
+-1e308 - 1e308
diff --git a/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet.golden
new file mode 100644
index 00000000..43eeae58
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.arithmetic_overflow_subtraction.jsonnet.golden
@@ -0,0 +1,2 @@
+sjsonnet.Error: overflow
+    at [<root>].(error.arithmetic_overflow_subtraction.jsonnet:2:8)