diff --git a/Makefile b/Makefile
index a35e8da9..69990ad4 100644
--- a/Makefile
+++ b/Makefile
@@ -19,6 +19,10 @@ ifeq ($(MACHINE),)
 else
 	CC_FLAGS += -DMACHINE_$(MACHINE)
 endif
+# Health instrumentation and the "health" console command: HEALTH=1 gmake ...
+ifneq ($(HEALTH),)
+	CC_FLAGS += -DHEALTH
+endif
 
 ifeq ($(CI),1)
 	CC_FLAGS += --Werror
diff --git a/cmd_parser.c b/cmd_parser.c
index a18b3837..30c55144 100644
--- a/cmd_parser.c
+++ b/cmd_parser.c
@@ -1849,8 +1849,10 @@ void cmd_parser(void) __banked
 			}
 		} else if (cmd_compare(0, "stp")) {
 			stp_parse();
+#ifdef HEALTH
 		} else if (cmd_compare(0, "health")) {
 			health_show();
+#endif
 		} else if (cmd_compare(0, "pvid")) {
 			if (cmd_words_len == 3 && cmd_parse_port_separator(cmd_words_b[1]) != 0
 			    && atoi_short(cmd_words_b[2]) && atoi_results_short && atoi_results_short <= 4094)
@@ -2050,6 +2052,7 @@ void execute_commands(__xdata uint8_t *p) __banked {
 	};
 }
 
+#ifdef HEALTH
 /*
  * Health instrumentation. The counters live in xdata and are fed from the
  * main loop through the banked entry points below; the "health" command
@@ -2205,3 +2208,4 @@ void health_show(void) __banked
 	print_short(management_vlan);
 	write_char('\n');
 }
+#endif
diff --git a/cmd_parser.h b/cmd_parser.h
index 9f140135..29d08c36 100644
--- a/cmd_parser.h
+++ b/cmd_parser.h
@@ -9,7 +9,10 @@ extern __xdata uint8_t cmd_buffer[CMD_BUF_SIZE];
 extern __xdata uint8_t cmd_available;
 extern __xdata uint8_t err_status;
 
-/* Phase ids of the health instrumentation, in main-loop order */
+/* Health instrumentation, built with HEALTH=1. Without it the hooks below
+ * compile to nothing and the "health" command does not exist. */
+#ifdef HEALTH
+/* Phase ids, in main-loop order */
 #define HEALTH_PH_LINK	0
 #define HEALTH_PH_SFP	1
 #define HEALTH_PH_RX	2
@@ -19,11 +22,18 @@ extern __xdata uint8_t err_status;
 #define HEALTH_PHASES	6
 
 extern __xdata uint16_t health_rx_frames;
+#define health_rx_frame()	health_rx_frames++
 
 void health_loop_start(void) __banked;	/* once per idle() pass, resets the phase baseline */
 void health_phase(uint8_t id) __banked;	/* after each phase; accounts ticks since last checkpoint */
 void health_stack_paint(void) __banked;	/* paint the unused stack area once at boot */
 void health_show(void) __banked;	/* "health" CLI dump */
+#else
+#define health_rx_frame()
+#define health_loop_start()
+#define health_phase(id)
+#define health_stack_paint()
+#endif
 
 void cmd_tokenize(void) __banked;
 void cmd_parser(void) __banked;
diff --git a/doc/health.md b/doc/health.md
index 08629b11..736d52b7 100644
--- a/doc/health.md
+++ b/doc/health.md
@@ -20,6 +20,17 @@ tcp st 00 tmr 00 rtx 00 rto 00 len 0x0000 mss 0x05b4
 httpd left 0x0000 entry 00 stp 01 mvlan 0x0002
 ```
 
+The instrumentation is not part of a default build. It costs about 1.1 kB
+of bank 2, a few bytes of xdata and seven banked calls per main-loop pass,
+which is nothing a user needs unless they are chasing a problem, so it is
+switched on at build time:
+
+```
+make MACHINE=SWTGW218AS HEALTH=1
+```
+
+Without it the hooks compile to nothing and `health` is not a command.
+
 All figures are raw hex. The counters are cumulative: take two dumps a known
 time apart and the differences give the rates.
 
diff --git a/rtlplayground.c b/rtlplayground.c
index 79a3d0b9..bd61c87c 100644
--- a/rtlplayground.c
+++ b/rtlplayground.c
@@ -1004,7 +1004,7 @@ void handle_rx(void)
 			REG_SET(RTL837X_REG_NIC_RXCMD, 1);
 			return;
 		}
-		health_rx_frames++;
+		health_rx_frame();
 
 #ifdef RXTXDBG
 		print_string("\n<< ");