diff --git a/src/main/java/net/javahippie/fitpub/service/FitFileService.java b/src/main/java/net/javahippie/fitpub/service/FitFileService.java
index bb7086e..a5b8b01 100644
--- a/src/main/java/net/javahippie/fitpub/service/FitFileService.java
+++ b/src/main/java/net/javahippie/fitpub/service/FitFileService.java
@@ -319,6 +319,7 @@ public class FitFileService {
         return activityRepository.findByIdAndUserId(activityId, userId)
             .map(activity -> {
                 activityRepository.delete(activity);
+                achievementService.rebuildAchievementsForUser(userId);
                 log.info("Deleted activity {} for user {}", activityId, userId);
                 return true;
             })
diff --git a/src/test/java/net/javahippie/fitpub/service/FitFileServiceTest.java b/src/test/java/net/javahippie/fitpub/service/FitFileServiceTest.java
index 3ad4b11..6f97fb8 100644
--- a/src/test/java/net/javahippie/fitpub/service/FitFileServiceTest.java
+++ b/src/test/java/net/javahippie/fitpub/service/FitFileServiceTest.java
@@ -238,6 +238,7 @@ class FitFileServiceTest {
         // Assert
         assertTrue(result);
         verify(activityRepository).delete(activity);
+        verify(achievementService).rebuildAchievementsForUser(testUserId);
     }
 
     @Test
@@ -254,6 +255,7 @@ class FitFileServiceTest {
         // Assert
         assertFalse(result);
         verify(activityRepository, never()).delete(any());
+        verify(achievementService, never()).rebuildAchievementsForUser(any());
     }
 
     @Test