diff --git a/src/include/ipxe/efi/efi.h b/src/include/ipxe/efi/efi.h
index 9554a6ad7..a73ef0959 100644
--- a/src/include/ipxe/efi/efi.h
+++ b/src/include/ipxe/efi/efi.h
@@ -84,6 +84,12 @@ struct efi_saved_tpl {
 	EFI_TPL previous;
 };
 
+/** An EFI dropped task priority level */
+struct efi_dropped_tpl {
+	/** Current TPL */
+	EFI_TPL current;
+};
+
 /** An EFI protocol used by iPXE */
 struct efi_protocol {
 	/** GUID */
@@ -408,6 +414,8 @@ extern EFI_STATUS efi_init ( EFI_HANDLE image_handle,
 			     EFI_SYSTEM_TABLE *systab );
 extern void efi_raise_tpl ( struct efi_saved_tpl *tpl );
 extern void efi_restore_tpl ( struct efi_saved_tpl *tpl );
+extern void efi_drop_tpl ( struct efi_dropped_tpl *tpl );
+extern void efi_undrop_tpl ( struct efi_dropped_tpl *tpl );
 extern int efi_open_untyped ( EFI_HANDLE handle, EFI_GUID *protocol,
 			      void **interface );
 extern int efi_open_unsafe_untyped ( EFI_HANDLE handle, EFI_GUID *protocol,
diff --git a/src/interface/efi/efi_connect.c b/src/interface/efi/efi_connect.c
index f4747cf6b..a4de78b78 100644
--- a/src/interface/efi/efi_connect.c
+++ b/src/interface/efi/efi_connect.c
@@ -59,6 +59,7 @@ int efi_connect ( EFI_HANDLE device, EFI_HANDLE driver ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	EFI_HANDLE driverlist[2] = { driver, NULL };
 	EFI_HANDLE *drivers = ( driver ? driverlist : NULL );
+	struct efi_dropped_tpl tpl;
 	EFI_STATUS efirc;
 	int rc;
 
@@ -67,9 +68,9 @@ int efi_connect ( EFI_HANDLE device, EFI_HANDLE driver ) {
 	DBGC ( device, "%s driver at %s TPL\n",
 	       ( driver ? efi_handle_name ( driver ) : "any" ),
 	       efi_tpl_name ( efi_external_tpl ) );
-	bs->RestoreTPL ( efi_external_tpl );
+	efi_drop_tpl ( &tpl );
 	efirc = bs->ConnectController ( device, drivers, NULL, TRUE );
-	bs->RaiseTPL ( efi_internal_tpl );
+	efi_undrop_tpl ( &tpl );
 	if ( efirc != 0 ) {
 		rc = -EEFI_CONNECT ( efirc );
 		DBGC ( device, "EFI %s could not connect: %s\n",
@@ -89,6 +90,7 @@ int efi_connect ( EFI_HANDLE device, EFI_HANDLE driver ) {
  */
 int efi_disconnect ( EFI_HANDLE device, EFI_HANDLE driver ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct efi_dropped_tpl tpl;
 	EFI_STATUS efirc;
 	int rc;
 
@@ -97,9 +99,9 @@ int efi_disconnect ( EFI_HANDLE device, EFI_HANDLE driver ) {
 	DBGC ( device, "%s driver at %s TPL\n",
 	       ( driver ? efi_handle_name ( driver ) : "any" ),
 	       efi_tpl_name ( efi_external_tpl ) );
-	bs->RestoreTPL ( efi_external_tpl );
+	efi_drop_tpl ( &tpl );
 	efirc = bs->DisconnectController ( device, driver, NULL );
-	bs->RaiseTPL ( efi_internal_tpl );
+	efi_undrop_tpl ( &tpl );
 	if ( ( efirc != 0 ) && ( efirc != EFI_NOT_FOUND ) ) {
 		rc = -EEFI ( efirc );
 		DBGC ( device, "EFI %s could not disconnect: %s\n",
diff --git a/src/interface/efi/efi_entropy.c b/src/interface/efi/efi_entropy.c
index b6bd12ccc..abd1018f3 100644
--- a/src/interface/efi/efi_entropy.c
+++ b/src/interface/efi/efi_entropy.c
@@ -50,6 +50,9 @@ struct entropy_source efitick_entropy __entropy_source ( ENTROPY_FALLBACK );
 /** Event used to wait for timer tick */
 static EFI_EVENT tick;
 
+/** Dropped TPL */
+static struct efi_dropped_tpl efi_entropy_tpl;
+
 /**
  * Enable entropy gathering
  *
@@ -61,7 +64,7 @@ static int efi_entropy_enable ( void ) {
 	int rc;
 
 	/* Drop to external TPL to allow timer tick event to take place */
-	bs->RestoreTPL ( efi_external_tpl );
+	efi_drop_tpl ( &efi_entropy_tpl );
 
 	/* Create timer tick event */
 	if ( ( efirc = bs->CreateEvent ( EVT_TIMER, TPL_NOTIFY, NULL, NULL,
@@ -92,7 +95,7 @@ static void efi_entropy_disable ( void ) {
 	bs->CloseEvent ( tick );
 
 	/* Return to internal TPL */
-	bs->RaiseTPL ( efi_internal_tpl );
+	efi_undrop_tpl ( &efi_entropy_tpl );
 }
 
 /**
diff --git a/src/interface/efi/efi_init.c b/src/interface/efi/efi_init.c
index ac62ea747..9fd2d0c6b 100644
--- a/src/interface/efi/efi_init.c
+++ b/src/interface/efi/efi_init.c
@@ -392,7 +392,7 @@ void efi_raise_tpl ( struct efi_saved_tpl *tpl ) {
 }
 
 /**
- * Restore task priority level
+ * Restore saved task priority level
  *
  * @v tpl		Saved TPL
  */
@@ -405,3 +405,31 @@ void efi_restore_tpl ( struct efi_saved_tpl *tpl ) {
 	/* Restore TPL */
 	bs->RestoreTPL ( tpl->current );
 }
+
+/**
+ * Drop task priority level temporarily to external level
+ *
+ * @v tpl		Dropped TPL
+ */
+void efi_drop_tpl ( struct efi_dropped_tpl *tpl ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+
+	/* Raise TPL temporarily to discover current TPL */
+	tpl->current = bs->RaiseTPL ( TPL_HIGH_LEVEL );
+	bs->RestoreTPL ( tpl->current );
+
+	/* Drop to external TPL */
+	bs->RestoreTPL ( efi_external_tpl );
+}
+
+/**
+ * Restore dropped task priority level
+ *
+ * @v tpl		Dropped TPL
+ */
+void efi_undrop_tpl ( struct efi_dropped_tpl *tpl ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+
+	/* Raise back to original TPL */
+	bs->RaiseTPL ( tpl->current );
+}
diff --git a/src/interface/efi/efi_timer.c b/src/interface/efi/efi_timer.c
index ffb899c86..66817f8f7 100644
--- a/src/interface/efi/efi_timer.c
+++ b/src/interface/efi/efi_timer.c
@@ -77,7 +77,7 @@ static void efi_udelay ( unsigned long usecs ) {
  * @ret ticks		Current time, in ticks
  */
 static unsigned long efi_currticks ( void ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct efi_dropped_tpl tpl;
 
 	/* UEFI manages to ingeniously combine the worst aspects of
 	 * both polling and interrupt-driven designs.  There is no way
@@ -137,8 +137,8 @@ static unsigned long efi_currticks ( void ) {
 	if ( efi_shutdown_in_progress ) {
 		efi_jiffies++;
 	} else {
-		bs->RestoreTPL ( efi_external_tpl );
-		bs->RaiseTPL ( efi_internal_tpl );
+		efi_drop_tpl ( &tpl );
+		efi_undrop_tpl ( &tpl );
 	}
 
 	return ( efi_jiffies * ( TICKS_PER_SEC / EFI_JIFFIES_PER_SEC ) );