diff --git a/libs/pbd/MSVCpbd/pbd.vcproj b/libs/pbd/MSVCpbd/pbd.vcproj
index 370ab93215..ebdaee1501 100644
--- a/libs/pbd/MSVCpbd/pbd.vcproj
+++ b/libs/pbd/MSVCpbd/pbd.vcproj
@@ -426,6 +426,10 @@
 				RelativePath="..\signals.cc"
 				>
 			</File>
+			<File
+				RelativePath="..\spinlock.cc"
+				>
+			</File>
 			<File
 				RelativePath="..\stacktrace.cc"
 				>
@@ -788,6 +792,10 @@
 				RelativePath="..\pbd\signals.h"
 				>
 			</File>
+			<File
+				RelativePath="..\pbd\spinlock.h"
+				>
+			</File>
 			<File
 				RelativePath="..\pbd\stacktrace.h"
 				>