diff --git a/src/reuse/_util.py b/src/reuse/_util.py
index d660435e..1ed068b3 100644
--- a/src/reuse/_util.py
+++ b/src/reuse/_util.py
@@ -319,14 +319,14 @@ def merge_copyright_lines(copyright_lines: Set[str]) -> Set[str]:
         ]
 
         # Get the most common prefix.
-        prefix = str(
+        most_common = str(
             Counter([item["prefix"] for item in copyright_list]).most_common(1)[
                 0
             ][0]
         )
         prefix = "spdx"
         for key, value in _COPYRIGHT_PREFIXES.items():
-            if prefix == value:
+            if most_common == value:
                 prefix = key
                 break