--- a/tests/Makefile.in	2026-04-20 21:28:12.589272400 +0200
+++ b/tests/Makefile.in	2026-04-20 21:28:55.471798246 +0200
@@ -711,7 +711,7 @@
 ################################################################################
 ### Minimal Fortran test.
 @QUO_WITH_MPIFC_TRUE@quofort_SOURCES = quofort.f90
-@QUO_WITH_MPIFC_TRUE@quofort_FCFLAGS = -I$(top_builddir)/src/fortran
+@QUO_WITH_MPIFC_TRUE@quofort_FCFLAGS = -I$(top_builddir)/src/fortran $(FCFLAGS)
 @QUO_WITH_MPIFC_TRUE@quofort_LDADD = \
 @QUO_WITH_MPIFC_TRUE@$(top_builddir)/src/fortran/libquo-usequo.la \
 @QUO_WITH_MPIFC_TRUE@$(top_builddir)/src/libquo.la