diff --git a/options/posix/generic/netdb-stubs.cpp b/options/posix/generic/netdb-stubs.cpp
index e858a092a5..455444bab8 100644
--- a/options/posix/generic/netdb-stubs.cpp
+++ b/options/posix/generic/netdb-stubs.cpp
@@ -480,3 +480,7 @@ void setservent(int) {
 	__builtin_unreachable();
 }
 
+const char *hstrerror(int) {
+	__ensure(!"Not implemented");
+	__builtin_unreachable();
+}
diff --git a/options/posix/include/netdb.h b/options/posix/include/netdb.h
index 90fc38e9b2..368c74f944 100644
--- a/options/posix/include/netdb.h
+++ b/options/posix/include/netdb.h
@@ -136,6 +136,9 @@ void setnetent(int);
 void setprotoent(int);
 void setservent(int);
 
+// Deprecated GNU extension
+const char *hstrerror(int err);
+
 #endif /* !__MLIBC_ABI_ONLY */
 
 #ifdef __cplusplus