Index: clang-tidy/cppcoreguidelines/SlicingCheck.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/SlicingCheck.cpp
+++ clang-tidy/cppcoreguidelines/SlicingCheck.cpp
@@ -122,10 +122,11 @@
       BaseDecl->getASTContext().getASTRecordLayout(BaseDecl);
   const auto &DerivedLayout =
       DerivedDecl->getASTContext().getASTRecordLayout(DerivedDecl);
-  const auto StateSize = DerivedLayout.getDataSize() - BaseLayout.getDataSize();
+  const CharUnits StateSize =
+      DerivedLayout.getDataSize() - BaseLayout.getDataSize();
   if (StateSize.isPositive()) {
     diag(Call->getExprLoc(), "slicing object from type %0 to %1 discards "
-                             "%2*sizeof(char) bytes of state")
+                             "%2 bytes of state")
         << DerivedDecl << BaseDecl << static_cast<int>(StateSize.getQuantity());
   }
 }
Index: test/clang-tidy/cppcoreguidelines-slicing.cpp
===================================================================
--- test/clang-tidy/cppcoreguidelines-slicing.cpp
+++ test/clang-tidy/cppcoreguidelines-slicing.cpp
@@ -31,18 +31,18 @@
 void positivesWithMemberVariables() {
   DerivedWithMemberVariables b;
   Base a{b};
-  // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}}*sizeof(char) bytes of state [cppcoreguidelines-slicing]
+  // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state [cppcoreguidelines-slicing]
   a = b;
-  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}}*sizeof(char) bytes of state
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
   TakesBaseByValue(b);
-  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}}*sizeof(char) bytes of state
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
 
   TwiceDerivedWithNoMemberVariables c;
   a = c;
-  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'TwiceDerivedWithNoMemberVariables' to 'Base' discards {{[0-9]*}}*sizeof(char) bytes of state
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'TwiceDerivedWithNoMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
 
   a = ReturnsDerived();
-  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}}*sizeof(char) bytes of state
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: slicing object from type 'DerivedWithMemberVariables' to 'Base' discards {{[0-9]*}} bytes of state
 }
 
 void positivesWithOverride() {