diff --git a/libc/decl/errno_values.h b/libc/decl/errno_values.h
index d52c6005..00e15313 100644
--- a/libc/decl/errno_values.h
+++ b/libc/decl/errno_values.h
@@ -58,6 +58,7 @@
 #define ECONNABORTED 66
 #define ECONNRESET 67
 #define EADDRNOTAVAIL 68
+#define EISCONN 69
 
 #define EOPNOTSUPP ENOTSUP
 
diff --git a/libc/strerror.cpp b/libc/strerror.cpp
index bfdc0c30..46c950d2 100644
--- a/libc/strerror.cpp
+++ b/libc/strerror.cpp
@@ -87,6 +87,7 @@ extern "C" const char* sortix_strerror(int errnum)
 	case ECONNABORTED: return "Connection aborted";
 	case ECONNRESET: return "Connection reset";
 	case EADDRNOTAVAIL: return "Address not available";
+	case EISCONN: return "Socket is connected";
 	default: return "Unknown error condition";
 	}
 }