diff --git a/OvmfPkg/Csm/CsmSupportLib/CsmSupportLib.inf b/OvmfPkg/Csm/CsmSupportLib/CsmSupportLib.inf
index 25056febf3..ba050cbb4f 100644
--- a/OvmfPkg/Csm/CsmSupportLib/CsmSupportLib.inf
+++ b/OvmfPkg/Csm/CsmSupportLib/CsmSupportLib.inf
@@ -30,6 +30,7 @@
 
 [Sources]
   CsmSupportLib.c
+  CsmSupportLib.h
   LegacyInterrupt.c
   LegacyPlatform.c
   LegacyRegion.c