diff --git a/src/add-ons/kernel/busses/usb/ehci.cpp b/src/add-ons/kernel/busses/usb/ehci.cpp
index 209c40fd25..c0fec9e373 100644
--- a/src/add-ons/kernel/busses/usb/ehci.cpp
+++ b/src/add-ons/kernel/busses/usb/ehci.cpp
@@ -2243,6 +2243,7 @@ EHCI::LinkDescriptors(ehci_qtd *first, ehci_qtd *last, ehci_qtd *alt)
 void
 EHCI::LinkITDescriptors(ehci_itd *itd, ehci_itd **_last)
 {
+	LockIsochronous();
 	ehci_itd *last = *_last;
 	itd->next_phy = last->next_phy;
 	itd->next = NULL;
@@ -2250,12 +2251,14 @@ EHCI::LinkITDescriptors(ehci_itd *itd, ehci_itd **_last)
 	last->next = itd;
 	last->next_phy = itd->this_phy;
 	*_last = itd;
+	UnlockIsochronous();
 }
 
 
 void
 EHCI::LinkSITDescriptors(ehci_sitd *sitd, ehci_sitd **_last)
 {
+	LockIsochronous();
 	ehci_sitd *last = *_last;
 	sitd->next_phy = last->next_phy;
 	sitd->next = NULL;
@@ -2263,29 +2266,34 @@ EHCI::LinkSITDescriptors(ehci_sitd *sitd, ehci_sitd **_last)
 	last->next = sitd;
 	last->next_phy = sitd->this_phy;
 	*_last = sitd;
+	UnlockIsochronous();
 }
 
 void
 EHCI::UnlinkITDescriptors(ehci_itd *itd, ehci_itd **last)
 {
+	LockIsochronous();
 	itd->prev->next_phy = itd->next_phy;
 	itd->prev->next = itd->next;
 	if (itd->next != NULL)
 		itd->next->prev = itd->prev;
 	if (itd == *last)
 		*last = itd->prev;
+	UnlockIsochronous();
 }
 
 
 void
 EHCI::UnlinkSITDescriptors(ehci_sitd *sitd, ehci_sitd **last)
 {
+	LockIsochronous();
 	sitd->prev->next_phy = sitd->next_phy;
 	sitd->prev->next = sitd->next;
 	if (sitd->next != NULL)
 		sitd->next->prev = sitd->prev;
 	if (sitd == *last)
 		*last = sitd->prev;
+	UnlockIsochronous();
 }