diff --git a/src/exchange_data_manager/cache/manager.py b/src/exchange_data_manager/cache/manager.py
index f2e399a..73c165c 100644
--- a/src/exchange_data_manager/cache/manager.py
+++ b/src/exchange_data_manager/cache/manager.py
@@ -189,6 +189,20 @@ class CacheManager:
             source = "exchange" if exchange_candles else "memory"
             return result, source
 
+        # Step 2b: Handle SINCE mode (start provided, no end)
+        # Gaps with end=None need to be fetched from exchange directly
+        import time as time_module
+        now = int(time_module.time())
+        normalized_gaps = []
+        for gap_start, gap_end in gaps_to_fill:
+            if gap_start is not None and gap_end is None:
+                # SINCE mode: fetch from start to now
+                normalized_gaps.append((gap_start, now))
+            elif gap_start is not None and gap_end is not None:
+                normalized_gaps.append((gap_start, gap_end))
+            # Skip gaps where start is None (shouldn't happen with proper request)
+        gaps_to_fill = normalized_gaps if normalized_gaps else gaps_to_fill
+
         db_hit = False
         exchange_hit = False