3 files changed, 3 insertions, 3 deletions
diff --git a/tests/cxx/tree/polymorphism/comparison/makefile b/tests/cxx/tree/polymorphism/comparison/makefile
index 5fe465f..de9dcdd 100644
--- a/tests/cxx/tree/polymorphism/comparison/makefile
+++ b/tests/cxx/tree/polymorphism/comparison/makefile
@@ -34,7 +34,7 @@ genf := $(xsd:.xsd=.hxx) $(xsd:.xsd=.ixx) $(xsd:.xsd=.cxx)
 gen  := $(addprefix $(out_base)/,$(genf))
 
 $(gen): xsd := $(out_root)/xsd/xsd
-$(gen): xsd_options := --generate-polymorphic --polymorphic-type base \
+$(gen): xsd_options += --generate-polymorphic --polymorphic-type base \
 --generate-comparison
 $(gen): $(out_root)/xsd/xsd
 
diff --git a/tests/cxx/tree/polymorphism/ostream/makefile b/tests/cxx/tree/polymorphism/ostream/makefile
index daf31ce..f38fcbd 100644
--- a/tests/cxx/tree/polymorphism/ostream/makefile
+++ b/tests/cxx/tree/polymorphism/ostream/makefile
@@ -34,7 +34,7 @@ genf := $(xsd:.xsd=.hxx) $(xsd:.xsd=.ixx) $(xsd:.xsd=.cxx)
 gen  := $(addprefix $(out_base)/,$(genf))
 
 $(gen): xsd := $(out_root)/xsd/xsd
-$(gen): xsd_options := --generate-polymorphic --polymorphic-type-all \
+$(gen): xsd_options += --generate-polymorphic --polymorphic-type-all \
 --root-element root --generate-ostream
 $(gen): $(out_root)/xsd/xsd
 
diff --git a/tests/cxx/tree/polymorphism/same-type/makefile b/tests/cxx/tree/polymorphism/same-type/makefile
index 3c66ef5..4e434c0 100644
--- a/tests/cxx/tree/polymorphism/same-type/makefile
+++ b/tests/cxx/tree/polymorphism/same-type/makefile
@@ -34,7 +34,7 @@ genf := $(xsd:.xsd=.hxx) $(xsd:.xsd=.ixx) $(xsd:.xsd=.cxx)
 gen  := $(addprefix $(out_base)/,$(genf))
 
 $(gen): xsd := $(out_root)/xsd/xsd
-$(gen): xsd_options := --generate-ostream --generate-polymorphic \
+$(gen): xsd_options += --generate-ostream --generate-polymorphic \
 --root-element root
 $(gen): $(out_root)/xsd/xsd