diff --git a/tools/distrib/gen_compilation_database.py b/tools/distrib/gen_compilation_database.py
index 5cda6d69e35..f2c93ade71c 100755
--- a/tools/distrib/gen_compilation_database.py
+++ b/tools/distrib/gen_compilation_database.py
@@ -90,6 +90,9 @@ def modifyCompileCommand(target, args):
     options = options.replace("-std=c++0x ", "")
     options = options.replace("-std=c++14 ", "")
 
+    # Add -DNDEBUG so that editors show the correct size information for structs.
+    options += " -DNDEBUG"
+
     if args.vscode:
         # Visual Studio Code doesn't seem to like "-iquote". Replace it with
         # old-style "-I".
diff --git a/tools/dockerfile/grpc_iwyu/iwyu.sh b/tools/dockerfile/grpc_iwyu/iwyu.sh
index 0a092a90869..20f2a77e2f1 100755
--- a/tools/dockerfile/grpc_iwyu/iwyu.sh
+++ b/tools/dockerfile/grpc_iwyu/iwyu.sh
@@ -37,7 +37,10 @@ cd ${IWYU_ROOT}
 sed -i 's,^#!/usr/bin/env python,#!/usr/bin/env python3,g' ${IWYU_ROOT}/iwyu/iwyu_tool.py
 sed -i 's,^#!/usr/bin/env python,#!/usr/bin/env python3,g' ${IWYU_ROOT}/iwyu/fix_includes.py
 
-cat compile_commands.json | sed "s,\"file\": \",\"file\": \"${IWYU_ROOT}/,g" > compile_commands_for_iwyu.json
+cat compile_commands.json                            \
+  | sed "s/ -DNDEBUG//g"                              \
+  | sed "s,\"file\": \",\"file\": \"${IWYU_ROOT}/,g" \
+  > compile_commands_for_iwyu.json
 
 export ENABLED_MODULES='
   src/core/ext