diff --git a/app/pages/settings.py b/app/pages/settings.py
index d77edf2..3974eb9 100644
--- a/app/pages/settings.py
+++ b/app/pages/settings.py
@@ -70,6 +70,15 @@ def settings_page(workspace_id: str) -> None:
             return str(int(parsed))
         return str(parsed)
 
+    def as_positive_int(value: object) -> int | None:
+        try:
+            parsed = float(value)
+        except (TypeError, ValueError):
+            return None
+        if parsed < 1 or not parsed.is_integer():
+            return None
+        return int(parsed)
+
     def last_saved_status_text(config: PortfolioConfig) -> str:
         return save_status_text(config).replace("Saved:", "Last saved:", 1)
 
@@ -78,6 +87,10 @@ def settings_page(workspace_id: str) -> None:
         if parsed_loan_amount is None:
             raise ValueError("Loan amount must be zero or greater")
 
+        parsed_refresh_interval = as_positive_int(refresh_interval.value)
+        if parsed_refresh_interval is None:
+            raise ValueError("Refresh interval must be a whole number of seconds")
+
         return PortfolioConfig(
             gold_value=as_positive_float(gold_value.value),
             entry_price=as_positive_float(entry_price.value),
@@ -89,7 +102,7 @@ def settings_page(workspace_id: str) -> None:
             ltv_warning=float(ltv_warning.value),
             primary_source=str(primary_source.value),
             fallback_source=str(fallback_source.value),
-            refresh_interval=int(refresh_interval.value),
+            refresh_interval=parsed_refresh_interval,
             volatility_spike=float(vol_alert.value),
             spot_drawdown=float(price_alert.value),
             email_alerts=bool(email_alerts.value),
diff --git a/tests/test_settings_validation_playwright.py b/tests/test_settings_validation_playwright.py
index 50eab94..d0e63da 100644
--- a/tests/test_settings_validation_playwright.py
+++ b/tests/test_settings_validation_playwright.py
@@ -20,8 +20,15 @@ def test_settings_reject_invalid_loan_amount_without_silent_zero_fallback() -> N
         expect(page.locator("text=Settings").first).to_be_visible(timeout=15000)
         expect(page.locator("text=Last saved:").first).to_be_visible(timeout=15000)
 
-        page.get_by_label("Refresh interval (seconds)").fill("7")
+        refresh_interval_input = page.get_by_label("Refresh interval (seconds)")
+        refresh_interval_input.fill("7")
         expect(page.locator("text=Unsaved changes — Last saved:").first).to_be_visible(timeout=15000)
+        refresh_interval_input.fill("5.5")
+        refresh_interval_input.press("Tab")
+        expect(page.locator("text=INVALID").first).to_be_visible(timeout=15000)
+        expect(page.locator("text=Refresh interval must be a whole number of seconds").first).to_be_visible(
+            timeout=15000
+        )
         page.reload(wait_until="domcontentloaded", timeout=30000)
         expect(page.get_by_label("Refresh interval (seconds)")).to_have_value("5")
         expect(page.locator("text=Last saved:").first).to_be_visible(timeout=15000)