diff --git a/promptlens/utils/retry.py b/promptlens/utils/retry.py
index 7834517..06e7fea 100644
--- a/promptlens/utils/retry.py
+++ b/promptlens/utils/retry.py
@@ -33,6 +33,18 @@ async def retry_with_exponential_backoff(
     Raises:
         Exception: The last exception if all retries fail
     """
+    if max_attempts < 1:
+        raise ValueError("max_attempts must be >= 1")
+
+    if initial_delay < 0:
+        raise ValueError("initial_delay must be >= 0")
+
+    if backoff_factor <= 0:
+        raise ValueError("backoff_factor must be > 0")
+
+    if max_delay <= 0:
+        raise ValueError("max_delay must be > 0")
+
     delay = initial_delay
     last_exception = None
 
diff --git a/tests/test_retry_hardening.py b/tests/test_retry_hardening.py
new file mode 100644
index 0000000..2d20729
--- /dev/null
+++ b/tests/test_retry_hardening.py
@@ -0,0 +1,39 @@
+import pytest
+
+from promptlens.utils.retry import retry_with_exponential_backoff
+
+
+@pytest.mark.asyncio
+async def test_retry_rejects_non_positive_attempts() -> None:
+    async def always_fails() -> str:
+        raise RuntimeError("boom")
+
+    with pytest.raises(ValueError, match="max_attempts"):
+        await retry_with_exponential_backoff(always_fails, max_attempts=0)
+
+
+@pytest.mark.asyncio
+async def test_retry_rejects_negative_initial_delay() -> None:
+    async def always_fails() -> str:
+        raise RuntimeError("boom")
+
+    with pytest.raises(ValueError, match="initial_delay"):
+        await retry_with_exponential_backoff(always_fails, initial_delay=-0.1)
+
+
+@pytest.mark.asyncio
+async def test_retry_rejects_invalid_backoff_factor() -> None:
+    async def always_fails() -> str:
+        raise RuntimeError("boom")
+
+    with pytest.raises(ValueError, match="backoff_factor"):
+        await retry_with_exponential_backoff(always_fails, backoff_factor=0)
+
+
+@pytest.mark.asyncio
+async def test_retry_rejects_non_positive_max_delay() -> None:
+    async def always_fails() -> str:
+        raise RuntimeError("boom")
+
+    with pytest.raises(ValueError, match="max_delay"):
+        await retry_with_exponential_backoff(always_fails, max_delay=0)