diff --git a/cvsslib/cvss3/calculations.py b/cvsslib/cvss3/calculations.py
index bf82d5e..70088b6 100644
--- a/cvsslib/cvss3/calculations.py
+++ b/cvsslib/cvss3/calculations.py
@@ -55,7 +55,7 @@ def calculate_modified_impact_sub_score(scope: ModifiedScope,
         (1 - modified_conf * conf_req) *
         (1 - modified_integ * integ_req) *
         (1 - modified_avail * avail_req),
-        0.915
+        D("0.915")
     )
 
     if scope == ModifiedScope.UNCHANGED.value:
@@ -144,4 +144,4 @@ def calculate(run_calculation, get):
 
     environment_score = run_calculation(calculate_environmental_score, override=override)
 
-    return float(base_score), float(temporal_score), float(environment_score)
\ No newline at end of file
+    return float(base_score), float(temporal_score), float(environment_score)