diff --git a/Makefile.flags b/Makefile.flags
index 7e1c6030c..ee4c518d8 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -105,7 +105,14 @@ LDLIBS += m
 endif
 
 ifeq ($(CONFIG_PAM),y)
-LDLIBS += pam pam_misc
+# libpam uses libpthread, so for static builds busybox must be linked to
+# libpthread. On some platforms that requires an explicit -lpthread, so
+# it should be in LDLIBS. For non-static builds, scripts/trylink will
+# take care of removing -lpthread if possible. (Not bothering to check
+# CONFIG_STATIC because even in a non-static build it could be that the
+# only libpam available is libpam.a, so -lpthread could still be
+# needed.)
+LDLIBS += pam pam_misc pthread
 endif
 
 ifeq ($(CONFIG_SELINUX),y)