diff --git a/include/config.h.in b/include/config.h.in
index d2d7baff8a..e8063e87ea 100644
--- a/include/config.h.in
+++ b/include/config.h.in
@@ -11,5 +11,6 @@
 #mesondefine U3_OS_ENDIAN_big
 
 #mesondefine U3_MEMORY_DEBUG
+#mesondefine U3_CPU_DEBUG
 
 #endif /*CONFIG_H*/
diff --git a/include/noun/trace.h b/include/noun/trace.h
index 5b847f5216..838ce835f3 100644
--- a/include/noun/trace.h
+++ b/include/noun/trace.h
@@ -2,12 +2,6 @@
 **
 ** This file is in the public domain.
 */
-  /**  Options.
-  **/
-    /* U3_CPU_DEBUG: activate profiling.
-    */
-#     undef U3_CPU_DEBUG
-
   /** Data structures.
   **/
     /* u3t_trace: fast execution flags.
diff --git a/meson.build b/meson.build
index d8c17808cb..4cefeff2ff 100644
--- a/meson.build
+++ b/meson.build
@@ -265,6 +265,7 @@ incdir = include_directories('include/')
 conf_data = configuration_data()
 conf_data.set('URBIT_VERSION', '"0.6.0"')
 conf_data.set('U3_MEMORY_DEBUG', get_option('gc'))
+conf_data.set('U3_CPU_DEBUG', get_option('prof'))
 
 osdet = build_machine.system()
 os_c_flags = ['-funsigned-char','-ffast-math']
diff --git a/meson_options.txt b/meson_options.txt
index 4f9bb057a1..a4dd843856 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -1,2 +1,4 @@
 option('gc', type : 'boolean', value : false,
   description : 'Add debugging information to heap. Run with -g. Breaks image.')
+option('prof', type : 'boolean', value : false,
+  description : 'Activate profiling. Run with -P.')