diff --git a/slurm/slurm.h.in b/slurm/slurm.h.in
index 0d06aada00b5914f4d1132e13017ae59e443f8a6..fdff8b197c2ed7063840c4f5e7e4e33014e9c4aa 100644
--- a/slurm/slurm.h.in
+++ b/slurm/slurm.h.in
@@ -2896,9 +2896,6 @@ typedef struct slurm_ctl_conf {
 	char *version;		/* version of slurmctld */
 	uint16_t vsize_factor;	/* virtual memory limit size factor */
 	uint16_t wait_time;	/* default job --wait time */
-	uint16_t z_16;		/* reserved for future use */
-	uint32_t z_32;		/* reserved for future use */
-	char *z_char;		/* reserved for future use */
 } slurm_ctl_conf_t;
 
 typedef struct slurmd_status_msg {
diff --git a/src/common/read_config.c b/src/common/read_config.c
index aa085e201fc0573052f996c98fdb05ef5c45b560..bad330ee6e11d5bc35f7a071635aec1ad66f312b 100644
--- a/src/common/read_config.c
+++ b/src/common/read_config.c
@@ -2424,7 +2424,6 @@ free_slurm_conf (slurm_ctl_conf_t *ctl_conf_ptr, bool purge_node_hash)
 	xfree (ctl_conf_ptr->topology_plugin);
 	xfree (ctl_conf_ptr->unkillable_program);
 	xfree (ctl_conf_ptr->version);
-	xfree (ctl_conf_ptr->z_char);
 
 	if (purge_node_hash)
 		_free_name_hashtbl();
diff --git a/src/common/slurm_protocol_pack.c b/src/common/slurm_protocol_pack.c
index bd370dad360b11a1b807d8e1159ab8f7ac7ed7b8..f063082c7d258f943ef55000281e2c9227d5c250 100644
--- a/src/common/slurm_protocol_pack.c
+++ b/src/common/slurm_protocol_pack.c
@@ -6630,9 +6630,6 @@ _pack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t * build_ptr, Buf buffer,
 		pack16(build_ptr->vsize_factor, buffer);
 
 		pack16(build_ptr->wait_time, buffer);
-		pack16(build_ptr->z_16, buffer);
-		pack32(build_ptr->z_32, buffer);
-		packstr(build_ptr->z_char, buffer);
 	} else if (protocol_version >= SLURM_17_02_PROTOCOL_VERSION) {
 		pack_time(build_ptr->last_update, buffer);
 
@@ -6912,9 +6909,9 @@ _pack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t * build_ptr, Buf buffer,
 		pack16(build_ptr->vsize_factor, buffer);
 
 		pack16(build_ptr->wait_time, buffer);
-		pack16(build_ptr->z_16, buffer);
-		pack32(build_ptr->z_32, buffer);
-		packstr(build_ptr->z_char, buffer);
+		pack16(0, buffer);
+		pack32(0, buffer);
+		packnull(buffer);
 	} else if (protocol_version >= SLURM_MIN_PROTOCOL_VERSION) {
 		pack_time(build_ptr->last_update, buffer);
 
@@ -7195,9 +7192,9 @@ _pack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t * build_ptr, Buf buffer,
 		pack16(build_ptr->vsize_factor, buffer);
 
 		pack16(build_ptr->wait_time, buffer);
-		pack16(build_ptr->z_16, buffer);
-		pack32(build_ptr->z_32, buffer);
-		packstr(build_ptr->z_char, buffer);
+		pack16(0, buffer);
+		pack32(0, buffer);
+		packnull(buffer);
 	} else {
 		error("_pack_slurm_ctl_conf_msg: protocol_version "
 		      "%hu not supported", protocol_version);
@@ -7625,12 +7622,9 @@ _unpack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t **build_buffer_ptr,
 		safe_unpack16(&build_ptr->vsize_factor, buffer);
 
 		safe_unpack16(&build_ptr->wait_time, buffer);
-
-		safe_unpack16(&build_ptr->z_16, buffer);
-		safe_unpack32(&build_ptr->z_32, buffer);
-		safe_unpackstr_xmalloc(&build_ptr->z_char, &uint32_tmp,
-				       buffer);
 	} else if (protocol_version >= SLURM_17_02_PROTOCOL_VERSION) {
+		char *charptr_tmp;
+
 		/* unpack timestamp of snapshot */
 
 		safe_unpack_time(&build_ptr->last_update, buffer);
@@ -8031,12 +8025,13 @@ _unpack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t **build_buffer_ptr,
 
 		safe_unpack16(&build_ptr->wait_time, buffer);
 
-		safe_unpack16(&build_ptr->z_16, buffer);
-		safe_unpack32(&build_ptr->z_32, buffer);
-		safe_unpackstr_xmalloc(&build_ptr->z_char, &uint32_tmp,
-				       buffer);
+		safe_unpack16(&uint16_tmp, buffer);
+		safe_unpack32(&uint32_tmp, buffer);
+		safe_unpackstr_xmalloc(&charptr_tmp, &uint32_tmp, buffer);
+		xfree(charptr_tmp);
 	} else if (protocol_version >= SLURM_MIN_PROTOCOL_VERSION) {
 		uint32_t tmp_mem;
+		char *charptr_tmp;
 		/* unpack timestamp of snapshot */
 		safe_unpack_time(&build_ptr->last_update, buffer);
 
@@ -8438,10 +8433,10 @@ _unpack_slurm_ctl_conf_msg(slurm_ctl_conf_info_msg_t **build_buffer_ptr,
 
 		safe_unpack16(&build_ptr->wait_time, buffer);
 
-		safe_unpack16(&build_ptr->z_16, buffer);
-		safe_unpack32(&build_ptr->z_32, buffer);
-		safe_unpackstr_xmalloc(&build_ptr->z_char, &uint32_tmp,
-				       buffer);
+		safe_unpack16(&uint16_tmp, buffer);
+		safe_unpack32(&uint32_tmp, buffer);
+		safe_unpackstr_xmalloc(&charptr_tmp, &uint32_tmp, buffer);
+		xfree(charptr_tmp);
 	} else {
 		error("_unpack_slurm_ctl_conf_msg: protocol_version "
 		      "%hu not supported", protocol_version);