diff --git a/.clang-format b/.clang-format
index 3a7e87a91..da767a304 100644
--- a/.clang-format
+++ b/.clang-format
@@ -1,17 +1,19 @@
 ---
-# This configuration requires clang-format 3.8 or higher.
+# This configuration requires clang-format 9 or higher.
 BasedOnStyle: Mozilla
 AlignAfterOpenBracket: Align
+AlignEscapedNewlines: true
 AlignOperands: false
-AlwaysBreakAfterReturnType: None
+AllowAllParametersOfDeclarationOnNextLine: false
 AlwaysBreakAfterDefinitionReturnType: None
-BreakBeforeBraces: Allman
+AlwaysBreakAfterReturnType: None
 BinPackArguments: false
 BinPackParameters: false
+BreakBeforeBraces: Allman
 ColumnLimit: 100
+# FixNamespaceComments: true
 MaxEmptyLinesToKeep: 4
-Standard: Cpp11
-# This requires clang-format 4.0 (at least).
-#FixNamespaceComments: true
 ReflowComments: false
+SpaceAfterTemplateKeyword: true
+Standard: Cpp11
 ...
diff --git a/.gitattributes b/.gitattributes
index db833f0a6..f67ede8d2 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,5 +1,5 @@
 # Attributes used for formatting.
-[attr]our-c-style   whitespace=tab-in-indent  format.clang-format
+[attr]our-c-style   whitespace=tab-in-indent  format.clang-format=9
 
 *.cxx   our-c-style
 *.h     our-c-style