diff --git a/compiler/common/charmonizer.main b/compiler/common/charmonizer.main
index 26ac692..8d8ea73 100644
--- a/compiler/common/charmonizer.main
+++ b/compiler/common/charmonizer.main
@@ -29,7 +29,7 @@
 } SourceFileContext;
 
 static void
-S_add_compiler_flags(struct chaz_CLIArgs *args) {
+S_add_compiler_flags(struct chaz_CLI *cli) {
     chaz_CFlags *extra_cflags = chaz_CC_get_extra_cflags();
 
     if (chaz_Probe_gcc_version_num()) {
@@ -41,7 +41,7 @@
                 "-DLUCY_DEBUG -pedantic -Wall -Wextra -Wno-variadic-macros"
             );
         }
-        if (args->charmony_pm) {
+        if (chaz_CLI_defined(cli, "enable-perl")) {
             chaz_CFlags_append(extra_cflags, "-DPERL_GCC_PEDANTIC");
         }
 
@@ -92,7 +92,7 @@
 }
 
 static void
-S_write_makefile(struct chaz_CLIArgs *args) {
+S_write_makefile(struct chaz_CLI *cli) {
     SourceFileContext sfc;
 
     const char *base_dir = "..";
@@ -140,7 +140,7 @@
     chaz_CFlags_add_include_dir(makefile_cflags, ".");
     chaz_CFlags_add_include_dir(makefile_cflags, include_dir);
     chaz_CFlags_add_include_dir(makefile_cflags, src_dir);
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_CFlags_enable_code_coverage(makefile_cflags);
     }
 
@@ -189,7 +189,7 @@
     if (chaz_CC_msvc_version_num()) {
         chaz_CFlags_append(link_flags, "/nologo");
     }
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_CFlags_enable_code_coverage(link_flags);
     }
     chaz_MakeFile_add_exe(makefile, cfc_exe, "$(COMMON_OBJS) $(CFC_OBJS)",
@@ -201,7 +201,7 @@
     rule = chaz_MakeFile_add_rule(makefile, "test", test_cfc_exe);
     chaz_MakeRule_add_command(rule, test_cfc_exe);
 
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         rule = chaz_MakeFile_add_rule(makefile, "coverage", test_cfc_exe);
         chaz_MakeRule_add_command(rule,
                                   "lcov"
@@ -228,7 +228,7 @@
     chaz_MakeRule_add_rm_command(clean_rule, "$(CFC_OBJS)");
     chaz_MakeRule_add_rm_command(clean_rule, "$(TEST_CFC_OBJS)");
 
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_MakeRule_add_rm_command(clean_rule, "cfc.info");
         chaz_MakeRule_add_recursive_rm_command(clean_rule, "coverage");
     }
@@ -250,14 +250,16 @@
 
 int main(int argc, const char **argv) {
     /* Initialize. */
-    struct chaz_CLIArgs args;
+    chaz_CLI *cli
+        = chaz_CLI_new(argv[0], "charmonizer: Probe C build environment");
+    chaz_CLI_set_usage(cli, "Usage: charmonizer [OPTIONS] [-- [CFLAGS]]");
     {
-        int result = chaz_Probe_parse_cli_args(argc, argv, &args);
+        int result = chaz_Probe_parse_cli_args(argc, argv, cli);
         if (!result) {
             chaz_Probe_die_usage();
         }
-        chaz_Probe_init(&args);
-        S_add_compiler_flags(&args);
+        chaz_Probe_init(cli);
+        S_add_compiler_flags(cli);
     }
 
     /* Define stdint types in charmony.h. */
@@ -278,11 +280,12 @@
     chaz_UnusedVars_run();
     chaz_VariadicMacros_run();
 
-    if (args.write_makefile) {
-        S_write_makefile(&args);
+    if (chaz_CLI_defined(cli, "enable-makefile")) {
+        S_write_makefile(cli);
     }
 
     /* Clean up. */
+    chaz_CLI_destroy(cli);
     chaz_Probe_clean_up();
 
     return 0;
diff --git a/runtime/common/charmonizer.main b/runtime/common/charmonizer.main
index 36a5d5b..4664782 100644
--- a/runtime/common/charmonizer.main
+++ b/runtime/common/charmonizer.main
@@ -33,6 +33,7 @@
 #include "Charmonizer/Probe/SymbolVisibility.h"
 #include "Charmonizer/Probe/VariadicMacros.h"
 #include "Charmonizer/Core/HeaderChecker.h"
+#include "Charmonizer/Core/CLI.h"
 #include "Charmonizer/Core/ConfWriter.h"
 #include "Charmonizer/Core/ConfWriterC.h"
 #include "Charmonizer/Core/ConfWriterPerl.h"
@@ -46,7 +47,7 @@
 static const char cfish_major_version[] = "0.4";
 
 static void
-S_add_compiler_flags(struct chaz_CLIArgs *args) {
+S_add_compiler_flags(struct chaz_CLI *cli) {
     chaz_CFlags *extra_cflags = chaz_CC_get_extra_cflags();
 
     if (chaz_Probe_gcc_version_num()) {
@@ -57,7 +58,7 @@
         else if (getenv("LUCY_DEBUG")) {
             chaz_CFlags_append(extra_cflags,
                 "-DLUCY_DEBUG -pedantic -Wall -Wextra -Wno-variadic-macros");
-            if (args->charmony_pm) {
+            if (chaz_CLI_defined(cli, "enable-perl")) {
                 chaz_CFlags_append(extra_cflags, "-DPERL_GCC_PEDANTIC");
             }
         }
@@ -131,7 +132,7 @@
 }
 
 static void
-S_write_makefile(struct chaz_CLIArgs *args) {
+S_write_makefile(struct chaz_CLI *cli) {
     SourceFileContext sfc;
 
     const char *base_dir = "..";
@@ -188,7 +189,7 @@
     chaz_CFlags_enable_debugging(makefile_cflags);
     chaz_CFlags_disable_strict_aliasing(makefile_cflags);
     chaz_CFlags_compile_shared_library(makefile_cflags);
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_CFlags_enable_code_coverage(makefile_cflags);
     }
 
@@ -265,7 +266,7 @@
     if (math_library) {
         chaz_CFlags_add_external_library(link_flags, math_library);
     }
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_CFlags_enable_code_coverage(link_flags);
     }
     chaz_MakeFile_add_shared_lib(makefile, shared_lib, "$(CLOWNFISH_OBJS)",
@@ -294,7 +295,7 @@
     }
     chaz_MakeRule_add_command(rule, test_command);
 
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         rule = chaz_MakeFile_add_rule(makefile, "coverage", test_cfish_exe);
         chaz_MakeRule_add_command(rule,
                                   "lcov"
@@ -319,7 +320,7 @@
     chaz_MakeRule_add_rm_command(clean_rule, "$(CLOWNFISH_OBJS)");
     chaz_MakeRule_add_recursive_rm_command(clean_rule, "autogen");
 
-    if (args->code_coverage) {
+    if (chaz_CLI_defined(cli, "enable-coverage")) {
         chaz_MakeRule_add_rm_command(clean_rule, "clownfish.info");
         chaz_MakeRule_add_recursive_rm_command(clean_rule, "coverage");
     }
@@ -351,14 +352,16 @@
 
 int main(int argc, const char **argv) {
     /* Initialize. */
-    struct chaz_CLIArgs args;
+    chaz_CLI *cli
+        = chaz_CLI_new(argv[0], "charmonizer: Probe C build environment");
+    chaz_CLI_set_usage(cli, "Usage: charmonizer [OPTIONS] [-- [CFLAGS]]");
     {
-        int result = chaz_Probe_parse_cli_args(argc, argv, &args);
+        int result = chaz_Probe_parse_cli_args(argc, argv, cli);
         if (!result) {
             chaz_Probe_die_usage();
         }
-        chaz_Probe_init(&args);
-        S_add_compiler_flags(&args);
+        chaz_Probe_init(cli);
+        S_add_compiler_flags(cli);
     }
     {
         int i;
@@ -420,11 +423,12 @@
         "#endif\n\n"
     );
 
-    if (args.write_makefile) {
-        S_write_makefile(&args);
+    if (chaz_CLI_defined(cli, "enable-makefile")) {
+        S_write_makefile(cli);
     }
 
     /* Clean up. */
+    chaz_CLI_destroy(cli);
     chaz_Probe_clean_up();
 
     return 0;