diff --git a/.clang-format b/.clang-format
index 36487f9c..4f806d16 100644
--- a/.clang-format
+++ b/.clang-format
@@ -20,6 +20,7 @@ BraceWrapping:
   AfterUnion:      true
 BreakBeforeBraces: Custom
 BreakConstructorInitializers: AfterColon
+ColumnLimit: 100
 DeriveLineEnding: false
 PackConstructorInitializers: Never
 IncludeCategories:
diff --git a/manual/contributing.rst b/manual/contributing.rst
index a6a612ec..0fb376e6 100644
--- a/manual/contributing.rst
+++ b/manual/contributing.rst
@@ -44,7 +44,7 @@ partial summary of the formatting rules:
 
 - Use spaces, not tabs.
 
-- Keep lines to 80 columns when possible.
+- Keep lines to 100 columns when possible.
 
 - Braces are on their own lines after classes and functions (and
   similar top-level constructs) and are compact otherwise.