diff --git a/src/arch/i386/transitions/librm_test.c b/src/arch/i386/transitions/librm_test.c
index 76ed1f7e8..8f5be4229 100644
--- a/src/arch/i386/transitions/librm_test.c
+++ b/src/arch/i386/transitions/librm_test.c
@@ -51,7 +51,8 @@ static struct profiler r2p_profiler __profiler = { .name = "r2p" };
  */
 static void librm_test_exec ( void ) {
 	unsigned int i;
-	unsigned long p2r_elapsed;
+	unsigned long timestamp;
+	unsigned int discard_d;
 
 	/* Profile mode transitions.  We want to profile each
 	 * direction of the transition separately, so perform an RDTSC
@@ -61,10 +62,11 @@ static void librm_test_exec ( void ) {
 	for ( i = 0 ; i < PROFILE_COUNT ; i++ ) {
 		profile_start ( &p2r_profiler );
 		__asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t" )
-				       : "=A" ( r2p_profiler.started ) : );
+				       : "=a" ( timestamp ), "=d" ( discard_d )
+				       : );
+		profile_start_at ( &r2p_profiler, timestamp );
 		profile_stop ( &r2p_profiler );
-		p2r_elapsed = ( r2p_profiler.started - p2r_profiler.started );
-		profile_update ( &p2r_profiler, p2r_elapsed );
+		profile_stop_at ( &p2r_profiler, timestamp );
 	}
 }
 
diff --git a/src/include/ipxe/profile.h b/src/include/ipxe/profile.h
index 0b15fe545..d4fc4f90f 100644
--- a/src/include/ipxe/profile.h
+++ b/src/include/ipxe/profile.h
@@ -9,7 +9,6 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
-#include <stdint.h>
 #include <bits/profile.h>
 #include <ipxe/tables.h>
 
@@ -26,7 +25,9 @@ struct profiler {
 	/** Name */
 	const char *name;
 	/** Start timestamp */
-	uint64_t started;
+	unsigned long started;
+	/** Stop timestamp */
+	unsigned long stopped;
 	/** Number of samples */
 	unsigned int count;
 	/** Mean sample value (scaled) */
@@ -62,6 +63,20 @@ extern unsigned long profile_mean ( struct profiler *profiler );
 extern unsigned long profile_variance ( struct profiler *profiler );
 extern unsigned long profile_stddev ( struct profiler *profiler );
 
+/**
+ * Start profiling
+ *
+ * @v profiler		Profiler
+ * @v started		Start timestamp
+ */
+static inline __attribute__ (( always_inline )) void
+profile_start_at ( struct profiler *profiler, unsigned long started ) {
+
+	/* If profiling is active then record start timestamp */
+	if ( PROFILING )
+		profiler->started = started;
+}
+
 /**
  * Start profiling
  *
@@ -72,7 +87,23 @@ profile_start ( struct profiler *profiler ) {
 
 	/* If profiling is active then record start timestamp */
 	if ( PROFILING )
-		profiler->started = profile_timestamp();
+		profile_start_at ( profiler, profile_timestamp() );
+}
+
+/**
+ * Record profiling result
+ *
+ * @v profiler		Profiler
+ * @v stopped		Stop timestamp
+ */
+static inline __attribute__ (( always_inline )) void
+profile_stop_at ( struct profiler *profiler, unsigned long stopped ) {
+
+	/* If profiling is active then record end timestamp and update stats */
+	if ( PROFILING ) {
+		profiler->stopped = stopped;
+		profile_update ( profiler, ( stopped - profiler->started ) );
+	}
 }
 
 /**
@@ -82,13 +113,10 @@ profile_start ( struct profiler *profiler ) {
  */
 static inline __attribute__ (( always_inline )) void
 profile_stop ( struct profiler *profiler ) {
-	uint64_t ended;
 
 	/* If profiling is active then record end timestamp and update stats */
-	if ( PROFILING ) {
-		ended = profile_timestamp();
-		profile_update ( profiler, ( ended - profiler->started ) );
-	}
+	if ( PROFILING )
+		profile_stop_at ( profiler, profile_timestamp() );
 }
 
 #endif /* _IPXE_PROFILE_H */