diff --git a/x-pack/plugins/observability/server/services/slo/historical_summary_client.ts b/x-pack/plugins/observability/server/services/slo/historical_summary_client.ts
index 2e582fd3eac84..41ff658c89de5 100644
--- a/x-pack/plugins/observability/server/services/slo/historical_summary_client.ts
+++ b/x-pack/plugins/observability/server/services/slo/historical_summary_client.ts
@@ -279,6 +279,7 @@ function generateSearchQuery(
               window: timeWindowDurationInDays * bucketsPerDay,
               shift: 1,
               script: 'MovingFunctions.sum(values)',
+              gap_policy: 'insert_zeros',
             },
           },
           cumulative_total: {
@@ -287,6 +288,7 @@ function generateSearchQuery(
               window: timeWindowDurationInDays * bucketsPerDay,
               shift: 1,
               script: 'MovingFunctions.sum(values)',
+              gap_policy: 'insert_zeros',
             },
           },
         },