diff --git a/puf/Makefile b/puf/Makefile
index 7935f605..1c4a0d42 100644
--- a/puf/Makefile
+++ b/puf/Makefile
@@ -24,6 +24,10 @@ WOLFSSL_ROOT ?= ../../wolfssl
 BUILD_DIR = ./Build
 BIN = puf_example
 
+# PUF test mode (default on): synthetic SRAM data for testing without hardware.
+# Set PUF_TEST=0 to build for real hardware SRAM.
+PUF_TEST ?= 1
+
 # Architecture
 ARCHFLAGS = -mcpu=cortex-m33 -mthumb -mabi=aapcs
 
@@ -33,6 +37,10 @@ CFLAGS += -ffunction-sections -fdata-sections -fno-builtin
 CFLAGS += -DWOLFSSL_USER_SETTINGS
 CFLAGS += -I. -I$(WOLFSSL_ROOT)
 
+ifeq ($(PUF_TEST),1)
+CFLAGS += -DWOLFSSL_PUF_TEST
+endif
+
 # Linker flags
 LDFLAGS = $(ARCHFLAGS)
 LDFLAGS += --specs=nosys.specs --specs=nano.specs
diff --git a/puf/user_settings.h b/puf/user_settings.h
index 94175bda..5d5d8450 100644
--- a/puf/user_settings.h
+++ b/puf/user_settings.h
@@ -47,9 +47,10 @@ extern "C" {
 #define WOLFSSL_PUF
 #define WOLFSSL_PUF_SRAM
 
-/* Enable test mode: allows synthetic SRAM data for testing without hardware.
- * Comment out to use real SRAM PUF on actual hardware. */
-#define WOLFSSL_PUF_TEST
+/* WOLFSSL_PUF_TEST enables test mode (synthetic SRAM data for testing
+ * without hardware). Controlled by the Makefile PUF_TEST switch:
+ *   make            (PUF_TEST=1, default) - test mode enabled
+ *   make PUF_TEST=0                       - real hardware SRAM PUF */
 
 /* ------------------------------------------------------------------------- */
 /* Required Dependencies */