diff --git a/libc/decl/errno_values.h b/libc/decl/errno_values.h
index 15e4b8a0..84ff6c5e 100644
--- a/libc/decl/errno_values.h
+++ b/libc/decl/errno_values.h
@@ -69,6 +69,7 @@
 #define ENOBUFS 77
 #define ENOMSG 78
 #define ENOPROTOOPT 79
+#define ENOTCONN 80
 
 #define EOPNOTSUPP ENOTSUP
 
diff --git a/libc/strerror.cpp b/libc/strerror.cpp
index 67bc627b..ffaaba95 100644
--- a/libc/strerror.cpp
+++ b/libc/strerror.cpp
@@ -98,6 +98,7 @@ extern "C" const char* sortix_strerror(int errnum)
 	case ENOBUFS: return "No buffer space available";
 	case ENOMSG: return "No message of the desired type";
 	case ENOPROTOOPT: return "Protocol not available";
+	case ENOTCONN: return "Socket is not connected";
 	default: return "Unknown error condition";
 	}
 }