diff --git a/CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc b/CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc
index ad1a6dcf60..d4b3f71157 100644
--- a/CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc
+++ b/CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc
@@ -88,7 +88,7 @@
   DEFINE SHELL_TYPE              = FULL_BIN
 
 [BuildOptions]
-  *_*_*_CC_FLAGS                 = /D DISABLE_NEW_DEPRECATED_INTERFACES
+  *_*_*_CC_FLAGS                 = -D DISABLE_NEW_DEPRECATED_INTERFACES
   GCC:*_UNIXGCC_*_CC_FLAGS       = -DMDEPKG_NDEBUG
   GCC:RELEASE_*_*_CC_FLAGS       = -DMDEPKG_NDEBUG
   INTEL:RELEASE_*_*_CC_FLAGS     = /D MDEPKG_NDEBUG
diff --git a/CorebootPayloadPkg/CorebootPayloadPkgIa32X64.dsc b/CorebootPayloadPkg/CorebootPayloadPkgIa32X64.dsc
index c06cccbf88..1e9bae9fb1 100644
--- a/CorebootPayloadPkg/CorebootPayloadPkgIa32X64.dsc
+++ b/CorebootPayloadPkg/CorebootPayloadPkgIa32X64.dsc
@@ -88,7 +88,7 @@
   DEFINE SHELL_TYPE              = FULL_BIN
 
 [BuildOptions]
-  *_*_*_CC_FLAGS                 = /D DISABLE_NEW_DEPRECATED_INTERFACES
+  *_*_*_CC_FLAGS                 = -D DISABLE_NEW_DEPRECATED_INTERFACES
   GCC:DEBUG_*_*_CC_FLAGS         = -Og -flto
   GCC:DEBUG_*_*_DLINK_FLAGS      = -flto
   GCC:*_UNIXGCC_*_CC_FLAGS       = -DMDEPKG_NDEBUG