diff --git a/libcli/smb/smb_util.h b/libcli/smb/smb_util.h
index 2884786339d..501b8dd1d3d 100644
--- a/libcli/smb/smb_util.h
+++ b/libcli/smb/smb_util.h
@@ -19,6 +19,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+const char *smb_protocol_types_string(enum protocol_types protocol);
 char *attrib_string(TALLOC_CTX *mem_ctx, uint32_t attrib);
 uint32_t unix_perms_to_wire(mode_t perms);
 mode_t wire_perms_to_unix(uint32_t perms);
diff --git a/libcli/smb/test_smb1cli_session.c b/libcli/smb/test_smb1cli_session.c
index e924b32e22e..d1e21d5431e 100644
--- a/libcli/smb/test_smb1cli_session.c
+++ b/libcli/smb/test_smb1cli_session.c
@@ -6,6 +6,7 @@
 #include "replace.h"
 #include <talloc.h>
 #include "libcli/util/ntstatus.h"
+#include "smb_constants.h"
 #include "smb_util.h"
 
 static const uint8_t smb1_session_setup_bytes[] = {
diff --git a/libcli/smb/util.c b/libcli/smb/util.c
index 7ef909c6077..6fdf35fbbf3 100644
--- a/libcli/smb/util.c
+++ b/libcli/smb/util.c
@@ -23,6 +23,44 @@
 #include "libcli/smb/smb_common.h"
 #include "system/filesys.h"
 
+const char *smb_protocol_types_string(enum protocol_types protocol)
+{
+	switch (protocol) {
+	case PROTOCOL_DEFAULT:
+		return "DEFAULT";
+	case PROTOCOL_NONE:
+		return "NONE";
+	case PROTOCOL_CORE:
+		return "CORE";
+	case PROTOCOL_COREPLUS:
+		return "COREPLUS";
+	case PROTOCOL_LANMAN1:
+		return "LANMAN1";
+	case PROTOCOL_LANMAN2:
+		return "LANMAN2";
+	case PROTOCOL_NT1:
+		return "NT1";
+	case PROTOCOL_SMB2_02:
+		return "SMB2_02";
+	case PROTOCOL_SMB2_10:
+		return "SMB2_10";
+	case PROTOCOL_SMB2_22:
+		return "SMB2_22";
+	case PROTOCOL_SMB2_24:
+		return "SMB2_24";
+	case PROTOCOL_SMB3_00:
+		return "SMB3_00";
+	case PROTOCOL_SMB3_02:
+		return "SMB3_02";
+	case PROTOCOL_SMB3_10:
+		return "SMB3_10";
+	case PROTOCOL_SMB3_11:
+		return "SMB3_11";
+	}
+
+	return "Invalid protocol_types value";
+}
+
 /**
  Return a string representing a CIFS attribute for a file.
 **/