diff --git a/Source/cmELF.cxx b/Source/cmELF.cxx
index 763fdd849..147f6accb 100644
--- a/Source/cmELF.cxx
+++ b/Source/cmELF.cxx
@@ -687,7 +687,7 @@ cmELFInternalImpl<Types>::GetDynamicSectionString(int tag)
       // The value has been read successfully.  Report it.
       se.Position = static_cast<unsigned long>(strtab.sh_offset + first);
       se.Size = last - first;
-      se.IndexInSection = di - this->DynamicSectionEntries.begin();
+      se.IndexInSection = static_cast<int>(di - this->DynamicSectionEntries.begin());
       return &se;
       }
     }