diff --git a/litescope/software/driver/analyzer.py b/litescope/software/driver/analyzer.py
index 8617971..007ca9b 100644
--- a/litescope/software/driver/analyzer.py
+++ b/litescope/software/driver/analyzer.py
@@ -91,6 +91,8 @@ class LiteScopeAnalyzerDriver:
         self.subsampler_value.write(value-1)
 
     def run(self, offset, length):
+        assert offset < self.depth
+        assert length <= self.depth
         if self.debug:
             print("[running]...")
         self.storage_offset.write(offset)