--- a/security/sandbox/win/wow_helper/Makefile.in
+++ b/security/sandbox/win/wow_helper/Makefile.in
@@ -25,17 +25,17 @@ CXX = $(call lazy,CXX,"$$(subst amd64_x8
 
 MOZ_WINCONSOLE = 0
 
 include $(topsrcdir)/config/config.mk
 
 # Munge the LIB variable to contain paths to the x64 CRT and system libraries.
 # Unconveniently, none of the paths have the same convention, including the
 # compiler path above.
-LIB = $(call lazy,LIB,$$(shell python -c 'import os; print ";".join(s.lower().replace(os.sep, "/").replace("/vc/lib", "/vc/lib/amd64").replace("/um/x86", "/um/x64") for s in os.environ["LIB"].split(";"))'))
+LIB = $(call lazy,LIB,$$(shell python -c 'import os; print ";".join(s.lower().replace(os.sep, "/").replace("/vc/lib", "/vc/lib/amd64").replace("/um/x86", "/um/x64").replace("/ucrt/x86", "/ucrt/x64") for s in os.environ["LIB"].split(";"))'))
 
 CXXFLAGS := $(filter-out -arch:IA32,$(CXXFLAGS))
 
 # OS_COMPILE_CXXFLAGS includes mozilla-config.h, which contains x86-specific
 # defines breaking the build.
 OS_COMPILE_CXXFLAGS :=
 
 # LNK1246: '/SAFESEH' not compatible with 'x64' target machine