diff --git a/tests/netdb_test.cpp b/tests/netdb_test.cpp
index a805693..0205707 100644
--- a/tests/netdb_test.cpp
+++ b/tests/netdb_test.cpp
@@ -265,11 +265,18 @@
   ASSERT_EQ(0, hp->h_addr[0]);
 }
 
+#if defined(MUSL)
+// musl doesn't define NETDB_INTERNAL.  It also never sets *err to -1, but
+// since gethostbyname_r is a glibc extension, the difference in behavior
+// between musl and  glibc should probably be considered a bug in musl.
+#define NETDB_INTERNAL -1
+#endif
+
 TEST(netdb, gethostbyname_r_ERANGE) {
   hostent hent;
   hostent *hp;
   char buf[4]; // Use too small buffer.
-  int err;
+  int err = 0;
   int result = gethostbyname_r("localhost", &hent, buf, sizeof(buf), &hp, &err);
   EXPECT_EQ(NETDB_INTERNAL, err);
   EXPECT_EQ(ERANGE, result);
@@ -280,7 +287,7 @@
   hostent hent;
   hostent *hp;
   char buf[4]; // Use too small buffer.
-  int err;
+  int err = 0;
   int result = gethostbyname2_r("localhost", AF_INET, &hent, buf, sizeof(buf), &hp, &err);
   EXPECT_EQ(NETDB_INTERNAL, err);
   EXPECT_EQ(ERANGE, result);
@@ -292,7 +299,7 @@
   hostent hent;
   hostent *hp;
   char buf[4]; // Use too small buffer.
-  int err;
+  int err = 0;
   int result = gethostbyaddr_r(&addr, sizeof(addr), AF_INET, &hent, buf, sizeof(buf), &hp, &err);
   EXPECT_EQ(NETDB_INTERNAL, err);
   EXPECT_EQ(ERANGE, result);