diff --git a/tests/unit/Makefile.am b/tests/unit/Makefile.am
index cb5bfc10013..80fe7311c46 100644
--- a/tests/unit/Makefile.am
+++ b/tests/unit/Makefile.am
@@ -39,27 +39,50 @@ nodist_%C%_test_zap_SOURCES = \
 
 
 # test run and coverage targets below
-PHONY += unit unit-coverage
+PHONY += unit unit-coverage unit-coverage-html
 
 _unit_run_%: %D%/%
 	@echo "  UNITTEST $<" ; $< $(TOPT)
 
-_unit_coverage_%: %D%/%
-	@${LCOV} --quiet --zerocounters --directory $(top_srcdir) >/dev/null
+# note: any changes in switches to lcov or genhtml must be carefully checked
+#       on 1.x and 2.x; the current option set is carefully chosen to allow
+#       both to work sensibly
+
+# .info is marked PRECIOUS, because its usually only created as an intermediate
+# from one of the unit phony targets, but once it exists there's no point
+# remaking it until and unless the test binary itself changes
+.PRECIOUS: %D%/%.info
+%D%/%.info: %D%/%
+	@-${RM} $@
+	@${LCOV} --quiet --quiet --zerocounters --directory $(top_srcdir)
 	@echo "  UNITTEST $<" ; $< $(TOPT)
-	@${LCOV} --quiet --capture  \
-		--test-name $(subst _unit_coverage_, , $@) \
+	@${LCOV} --quiet --quiet --capture  \
+		--test-name $(notdir $<) \
 		--directory $(top_srcdir) \
-		--output-file \
-			%D%/$(join $(subst _unit_coverage_, , $@), .info) \
-		$(addprefix --include , $(call $(join \
-			$(subst _unit_coverage_, nodist_%C%_, $@), _SOURCES)))
-	@${GENHTML} --quiet \
-		%D%/$(join $(subst _unit_coverage_, , $@), .info) \
-		--output-directory \
-			%D%/$(join $(subst _unit_coverage_, , $@), _coverage)
+		--output-file $@ \
+		--rc lcov_branch_coverage=1 \
+		--rc geninfo_unexecuted_blocks=1 \
+		$(addprefix --include $(abs_top_builddir)/, $(call \
+		    $(join $(join nodist_%C%_, $(notdir $<)), _SOURCES))) \
+		2>/dev/null
+
+_unit_coverage_%: %D%/%.info
+	@scripts/coverage_report.pl $<
+
+_unit_coverage_html_%: %D%/%.info
+	@-${RM} -r $(subst .info,_coverage, $<)
+	@${GENHTML} --quiet -quiet \
+		--rc lcov_branch_coverage=1 \
+		--rc check_data_consistency=0 \
+		--output-directory $(subst .info,_coverage, $<) \
+		$< \
+		2>/dev/null
 	@echo "coverage results:" \
-		"file://$(realpath %D%)/$(join $(subst _unit_coverage_, , $@), _coverage)/index.html"
+		"file://$(realpath %D%)/$(subst .info,_coverage,$(notdir $<))/index.html"
+
+CLEAN_LOCAL += unit-clean-local
+unit-clean-local:
+	-${RM} -r %D%/*.info %D%/*_coverage/
 
 _UNIT_ALL_TARGETS = $(notdir $(UNIT_TESTS))
 _UNIT_FIND_TARGET = \
@@ -76,9 +99,12 @@ unit: $(addprefix _unit_run_, $(_UNIT_TARGETS))
 if CODE_COVERAGE_ENABLED
 unit-coverage: $(addprefix _unit_coverage_, $(_UNIT_TARGETS))
 	@$(if $^, true, echo "ERROR: couldn't find unit test: $(T)" && false)
+unit-coverage-html: $(addprefix _unit_coverage_html_, $(_UNIT_TARGETS))
+	@$(if $^, true, echo "ERROR: couldn't find unit test: $(T)" && false)
 else
 unit-coverage:
 	@echo "unit test coverage not enabled."
 	@echo "re-run configure with --enable-code-coverage"
 	@false
+unit-coverage-html: unit-coverage
 endif