diff --git a/libc/decl/errno_values.h b/libc/decl/errno_values.h
index 4355c7dd..3735cab9 100644
--- a/libc/decl/errno_values.h
+++ b/libc/decl/errno_values.h
@@ -48,6 +48,7 @@
 #define EPROTONOSUPPORT 56
 #define EAFNOSUPPORT 57
 #define ENOTSOCK 58
+#define EADDRINUSE 59
 
 #define EOPNOTSUPP ENOTSUP
 
diff --git a/libc/strerror.cpp b/libc/strerror.cpp
index 3f4982f1..bcd4d331 100644
--- a/libc/strerror.cpp
+++ b/libc/strerror.cpp
@@ -77,6 +77,7 @@ extern "C" const char* sortix_strerror(int errnum)
 	case EPROTONOSUPPORT: return "Protocol not supported";
 	case EAFNOSUPPORT: return "Address family not supported";
 	case ENOTSOCK: return "Not a socket";
+	case EADDRINUSE: return "Address already in use";
 	default: return "Unknown error condition";
 	}
 }