diff --git a/headers/build/BeOSBuildCompatibility.h b/headers/build/BeOSBuildCompatibility.h
index 875897ca07..95c00d0edf 100644
--- a/headers/build/BeOSBuildCompatibility.h
+++ b/headers/build/BeOSBuildCompatibility.h
@@ -44,8 +44,12 @@ extern "C" {
 #endif
 
 // Is kernel-only under Linux.
+#ifndef strlcpy
 extern size_t   strlcpy(char* dest, const char* source, size_t length);
+#endif
+#ifndef strlcat
 extern size_t	strlcat(char* dest, const char* source, size_t length);
+#endif
 
 #if defined(HAIKU_HOST_PLATFORM_FREEBSD) || defined(HAIKU_HOST_PLATFORM_DARWIN)
 extern size_t	strnlen(const char* string, size_t length);