diff --git a/Makefile.inc b/Makefile.inc
index 89bb3e4239..a51b73d36b 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -411,6 +411,10 @@ CPPFLAGS_common += -include $(src)/commonlib/bsd/include/commonlib/bsd/compiler.
 CPPFLAGS_common += -I3rdparty
 CPPFLAGS_common += -D__BUILD_DIR__=\"$(obj)\"
 
+ifeq ($(BUILD_TIMELESS),1)
+CPPFLAGS_common += -D__TIMELESS__
+endif
+
 ifeq ($(CONFIG_PCI_OPTION_ROM_RUN_YABEL)$(CONFIG_PCI_OPTION_ROM_RUN_REALMODE),y)
 CPPFLAGS_ramstage += -Isrc/device/oprom/include
 endif
diff --git a/src/include/assert.h b/src/include/assert.h
index f656d81683..8c19c1cfee 100644
--- a/src/include/assert.h
+++ b/src/include/assert.h
@@ -12,31 +12,41 @@
 #undef ASSERT
 #endif
 
+/* Do not use filenames nor line numbers on timeless builds, to preserve reproducibility */
+#if ENV_TIMELESS
+#define __ASSERT_FILE__ "(filenames not available on timeless builds)"
+#define __ASSERT_LINE__ 404
+#else
+#define __ASSERT_FILE__ __FILE__
+#define __ASSERT_LINE__ __LINE__
+#endif
+
 /* GCC and CAR versions */
-#define ASSERT(x) {						\
-	if (!(x)) {						\
-		printk(BIOS_EMERG, "ASSERTION ERROR: file '%s'"	\
-			", line %d\n", __FILE__, __LINE__);	\
-		if (CONFIG(FATAL_ASSERTS))		\
-			hlt();					\
-	}							\
+#define ASSERT(x) {							\
+	if (!(x)) {							\
+		printk(BIOS_EMERG,					\
+			"ASSERTION ERROR: file '%s', line %d\n",	\
+			__ASSERT_FILE__, __ASSERT_LINE__);		\
+		if (CONFIG(FATAL_ASSERTS))				\
+			hlt();						\
+	}								\
 }
-
-#define ASSERT_MSG(x, msg) {					\
-	if (!(x)) {						\
-		printk(BIOS_EMERG, "ASSERTION ERROR: file '%s'"	\
-			", line %d\n", __FILE__, __LINE__);	\
-		printk(BIOS_EMERG, "%s", msg);                  \
-		if (CONFIG(FATAL_ASSERTS))			\
-			hlt();					\
-	}							\
+#define ASSERT_MSG(x, msg) {						\
+	if (!(x)) {							\
+		printk(BIOS_EMERG,					\
+			"ASSERTION ERROR: file '%s', line %d\n",	\
+			__ASSERT_FILE__, __ASSERT_LINE__);		\
+		printk(BIOS_EMERG, "%s", msg);				\
+		if (CONFIG(FATAL_ASSERTS))				\
+			hlt();						\
+	}								\
 }
-
-#define BUG() {							\
-	printk(BIOS_EMERG, "ERROR: BUG ENCOUNTERED at file '%s'"\
-		", line %d\n", __FILE__, __LINE__);		\
-	if (CONFIG(FATAL_ASSERTS))			\
-		hlt();						\
+#define BUG() {								\
+	printk(BIOS_EMERG,						\
+		"ERROR: BUG ENCOUNTERED at file '%s', line %d\n",	\
+		__ASSERT_FILE__, __ASSERT_LINE__);			\
+	if (CONFIG(FATAL_ASSERTS))					\
+		hlt();							\
 }
 
 #define assert(statement)	ASSERT(statement)
diff --git a/src/include/rules.h b/src/include/rules.h
index 160829efa4..2cc54e7942 100644
--- a/src/include/rules.h
+++ b/src/include/rules.h
@@ -3,6 +3,12 @@
 #ifndef _RULES_H
 #define _RULES_H
 
+#if defined(__TIMELESS__)
+#define ENV_TIMELESS 1
+#else
+#define ENV_TIMELESS 0
+#endif
+
 /* Useful helpers to tell whether the code is executing in bootblock,
  * romstage, ramstage or SMM.
  */