Fix compiler flags
diff --git a/templates/Makefile.template b/templates/Makefile.template
index b52354c..91f26a3 100644
--- a/templates/Makefile.template
+++ b/templates/Makefile.template
@@ -165,7 +165,7 @@
CXX11_CHECK_CMD = $(CXX) -std=c++11 -o $(TMPOUT) -c test/build/c++11.cc
HAS_CXX11 = $(shell $(CXX11_CHECK_CMD) 2> /dev/null && echo true || echo false)
- CHECK_NO_SHIFT_NEGATIVE_VALUE_CMD = $(CC) -std=c99 -Wno-shift-negative-value -o $(TMPOUT) -c test/build/empty.c
+ CHECK_NO_SHIFT_NEGATIVE_VALUE_CMD = $(CC) -std=c99 -Werror -Wno-shift-negative-value -o $(TMPOUT) -c test/build/empty.c
HAS_NO_SHIFT_NEGATIVE_VALUE = $(shell $(CHECK_NO_SHIFT_NEGATIVE_VALUE_CMD) 2> /dev/null && echo true || echo false)
ifeq ($(HAS_NO_SHIFT_NEGATIVE_VALUE),true)
W_NO_SHIFT_NEGATIVE_VALUE=-Wno-shift-negative-value