diff --git a/Makerules b/Makerules
index 275110dda8..c8b54f7d9a 100644
--- a/Makerules
+++ b/Makerules
@@ -469,9 +469,13 @@ S-CPPFLAGS = -DASSEMBLER $(asm-CPPFLAGS)
 
 ifneq (,$(objpfx))
 # Continuation lines here are dangerous because they introduce spaces!
+# Also remove the /usr/include/tgmath.h dependency generated by Clang
+# even though Clang never reads /usr/include/tgmath.h.
 define sed-remove-objpfx
 -e 's@ $(subst .,\.,$(subst @,\@,$(common-objpfx)))@ $$(common-objpfx)@g' \
--e 's@^$(subst .,\.,$(subst @,\@,$(common-objpfx)))@$$(common-objpfx)@g'
+-e 's@^$(subst .,\.,$(subst @,\@,$(common-objpfx)))@$$(common-objpfx)@g' \
+-e 's@/usr/include/tgmath.h:@@' \
+-e 's@ /usr/include/tgmath.h@@'
 endef
 endif