diff --git a/tests/unix-tty/makefile b/tests/unix-tty/makefile
index eb3509840..70f45f130 100644
--- a/tests/unix-tty/makefile
+++ b/tests/unix-tty/makefile
@@ -2,7 +2,9 @@ FBC := fbc
 CXX := g++
 
 FBFLAGS :=
-CXXFLAGS := -O2 -g
+# tester.cxx uses std::optional, which needs C++17; Apple clang does not
+# default to it, and this suite is where -dylib is exercised on Darwin.
+CXXFLAGS := -O2 -g -std=c++17
 LDFLAGS :=
 
 ALLFBFLAGS := $(FBFLAGS)
@@ -12,7 +14,15 @@ ALLLDFLAGS := $(LDFLAGS)
 TESTEE_SOURCES := $(sort $(wildcard testee-*.bas))
 TESTEE_BINARIES := $(patsubst %.bas,%,$(TESTEE_SOURCES))
 
-ALL_BINARIES := tester $(TESTEE_BINARIES) libexamplelib.so examplebin
+# Mach-O uses .dylib for shared libraries, ELF targets use .so
+ifeq ($(shell uname -s),Darwin)
+LIBEXT := .dylib
+else
+LIBEXT := .so
+endif
+LIBEXAMPLELIB := libexamplelib$(LIBEXT)
+
+ALL_BINARIES := tester $(TESTEE_BINARIES) $(LIBEXAMPLELIB) examplebin
 
 all: $(ALL_BINARIES)
 
@@ -25,7 +35,7 @@ $(TESTEE_BINARIES): %: %.bas
 # #include dependency
 testee-dylibload-dylibfree-examplelib: testee-dylibload-only-examplelib.bas
 
-libexamplelib.so: examplelib.bas
+$(LIBEXAMPLELIB): examplelib.bas
 	$(FBC) $(ALLFBFLAGS) $< -dylib
 
 examplebin: examplebin.bas
diff --git a/tests/unix-tty/tester.cxx b/tests/unix-tty/tester.cxx
index cde19040c..aac8056c8 100644
--- a/tests/unix-tty/tester.cxx
+++ b/tests/unix-tty/tester.cxx
@@ -57,7 +57,10 @@ std::string dump_tty_state(const struct termios &state) {
 	s << "  c_oflag=0x" << std::hex << state.c_oflag << '\n';
 	s << "  c_cflag=0x" << std::hex << state.c_cflag << '\n';
 	s << "  c_lflag=0x" << std::hex << state.c_lflag << '\n';
+#ifdef __linux__
+	// c_line is a Linux extension; the BSDs, Darwin included, have no such field
 	s << "  c_line=0x" << std::hex << static_cast<unsigned int>(state.c_line) << '\n';
+#endif
 	for (size_t i = 0; i < NCCS; ++i) {
 		s << "  c_cc[" << std::dec << i << "]=0x" << std::hex << static_cast<unsigned int>(state.c_cc[i]) << '\n';
 	}
@@ -80,7 +83,9 @@ void check_tty_state_is_equal(const struct termios &a, const struct termios &b)
 	CHECK(c_oflag);
 	CHECK(c_cflag);
 	CHECK(c_lflag);
+#ifdef __linux__
 	CHECK(c_line);
+#endif
 	for (size_t i = 0; i < NCCS; ++i) {
 		if (a.c_cc[i] != b.c_cc[i]) {
 			std::ostringstream s;