diff --git a/meson.build b/meson.build
index b45814c65c..65e3f038b9 100644
--- a/meson.build
+++ b/meson.build
@@ -3757,18 +3757,16 @@ endif
 if targetos == 'darwin'
   summary_info += {'Objective-C compiler': ' '.join(meson.get_compiler('objc').cmd_array())}
 endif
-summary_info += {'CFLAGS':            ' '.join(get_option('c_args')
-                                               + ['-O' + get_option('optimization')]
-                                               + (get_option('debug') ? ['-g'] : []))}
+option_cflags = (get_option('debug') ? ['-g'] : [])
+if get_option('optimization') != 'plain'
+  option_cflags += ['-O' + get_option('optimization')]
+endif
+summary_info += {'CFLAGS':            ' '.join(get_option('c_args') + option_cflags)}
 if link_language == 'cpp'
-  summary_info += {'CXXFLAGS':        ' '.join(get_option('cpp_args')
-                                               + ['-O' + get_option('optimization')]
-                                               + (get_option('debug') ? ['-g'] : []))}
+  summary_info += {'CXXFLAGS':        ' '.join(get_option('cpp_args') + option_cflags)}
 endif
 if targetos == 'darwin'
-  summary_info += {'OBJCFLAGS':       ' '.join(get_option('objc_args')
-                                               + ['-O' + get_option('optimization')]
-                                               + (get_option('debug') ? ['-g'] : []))}
+  summary_info += {'OBJCFLAGS':       ' '.join(get_option('objc_args') + option_cflags)}
 endif
 link_args = get_option(link_language + '_link_args')
 if link_args.length() > 0