diff --git a/tmk_core/protocol/usb_descriptor.c b/tmk_core/protocol/usb_descriptor.c
index c88aceb6e..7a4a79031 100644
--- a/tmk_core/protocol/usb_descriptor.c
+++ b/tmk_core/protocol/usb_descriptor.c
@@ -953,10 +953,10 @@ const USB_Descriptor_String_t PROGMEM ProductString = {
 #if defined(SERIAL_NUMBER)
 const USB_Descriptor_String_t PROGMEM SerialNumberString = {
     .Header = {
-        .Size                   = USB_STRING_LEN(sizeof(STR(SERIAL_NUMBER)) - 1), // Subtract 1 for null terminator
+        .Size                   = USB_STRING_LEN(sizeof(SERIAL_NUMBER) - 1), // Subtract 1 for null terminator
         .Type                   = DTYPE_String
     },
-    .UnicodeString              = LSTR(SERIAL_NUMBER)
+    .UnicodeString              = USBSTR(SERIAL_NUMBER)
 };
 #endif
 
diff --git a/tmk_core/protocol/usb_descriptor_common.h b/tmk_core/protocol/usb_descriptor_common.h
index b1f602c82..ce0cf0976 100644
--- a/tmk_core/protocol/usb_descriptor_common.h
+++ b/tmk_core/protocol/usb_descriptor_common.h
@@ -16,6 +16,10 @@
 
 #pragma once
 
+// Prefix string literal with L for descriptors
+#define USBCONCAT(a, b) a##b
+#define USBSTR(s) USBCONCAT(L, s)
+
 /////////////////////
 // RAW Usage page and ID configuration
 
diff --git a/tmk_core/protocol/vusb/vusb.c b/tmk_core/protocol/vusb/vusb.c
index 876a31378..98cebf601 100644
--- a/tmk_core/protocol/vusb/vusb.c
+++ b/tmk_core/protocol/vusb/vusb.c
@@ -599,10 +599,10 @@ const PROGMEM usbStringDescriptor_t usbStringDescriptorProduct = {
 #if defined(SERIAL_NUMBER)
 const PROGMEM usbStringDescriptor_t usbStringDescriptorSerial = {
     .header = {
-        .bLength         = USB_STRING_LEN(sizeof(STR(SERIAL_NUMBER)) - 1),
+        .bLength         = USB_STRING_LEN(sizeof(SERIAL_NUMBER) - 1),
         .bDescriptorType = USBDESCR_STRING
     },
-    .bString             = LSTR(SERIAL_NUMBER)
+    .bString             = USBSTR(SERIAL_NUMBER)
 };
 #endif