diff --git a/sql/Makefile b/sql/Makefile
index 5fc56d0..8a870d3 100644
--- a/sql/Makefile
+++ b/sql/Makefile
@@ -1,71 +1,71 @@
 # Depends: postgresql-client, postgresql-autodoc
 
 DBNAME = softwareheritage-scheduler-dev
 DOCDIR = autodoc
 
 SQL_SCHEMA  = 30-swh-schema.sql
 SQL_DATA    = 40-swh-data.sql
 SQLS = $(SQL_SCHEMA) $(SQL_DATA)
 SQL_FILES = $(abspath $(addprefix $(CURDIR)/../swh/scheduler/sql/,$(SQLS)))
 
 PSQL_BIN = psql
 PSQL_FLAGS = --echo-all -X -v ON_ERROR_STOP=1
 PSQL = $(PSQL_BIN) $(PSQL_FLAGS)
 
 PIFPAF=$(findstring postgresql://,$(PIFPAF_URLS))
 
 all:
 
 createdb: createdb-stamp
 createdb-stamp: $(SQL_FILES)
-ifndef PIFPAF
+ifeq ($(PIFPAF),)
 	-dropdb $(DBNAME)
 endif
 	createdb $(DBNAME)
-ifndef PIFPAF
+ifeq ($(PIFPAF),)
 	touch $@
 else
 	rm -f $@
 endif
 
 filldb: filldb-stamp
 filldb-stamp: createdb-stamp
 	cat $(SQL_FILES) | $(PSQL) $(DBNAME)
-ifndef PIFPAF
+ifeq ($(PIFPAF),)
 	touch $@
 else
 	rm -f $@
 endif
 
 dropdb:
 	-dropdb $(DBNAME)
 
 dumpdb: swh-scheduler.dump
 swh-scheduler.dump: filldb-stamp
 	pg_dump -Fc $(DBNAME) > $@
 
 $(DOCDIR):
 	test -d $(DOCDIR)/ || mkdir $(DOCDIR)
 
 doc: autodoc-stamp $(DOCDIR)/swh-scheduler.pdf
 autodoc-stamp: filldb-stamp $(DOCDIR)
 	postgresql_autodoc -d $(DBNAME) -f $(DOCDIR)/swh-scheduler
 	cp -a $(DOCDIR)/swh-scheduler.dot $(DOCDIR)/swh-scheduler.dot.orig
-ifndef PIFPAF
+ifeq ($(PIFPAF),)
 	touch $@
 else
 	rm -f $@
 endif
 
 $(DOCDIR)/swh-scheduler.pdf: $(DOCDIR)/swh-scheduler.dot autodoc-stamp
 	dot -T pdf $< > $@
 $(DOCDIR)/swh-scheduler.svg: $(DOCDIR)/swh-scheduler.dot autodoc-stamp
 	dot -T svg $< > $@
 
 clean:
 	rm -rf *-stamp $(DOCDIR)/
 
 distclean: clean dropdb
 	rm -f swh-scheduler.dump
 
 .PHONY: all initdb createdb dropdb doc clean