diff --git a/src/addr_util.cpp b/src/addr_util.cpp
index 27232b91..67a0d2cf 100644
--- a/src/addr_util.cpp
+++ b/src/addr_util.cpp
@@ -19,8 +19,8 @@ bool string_to_addr(std::string str, bool parse_port, int default_port, struct s
         if (p != std::string::npos && !(str.length() > 0 && str[p-1] == ']')) // "[ipv6]" which contains ':'
         {
             char null_byte = 0;
-            int n = sscanf(str.c_str()+p+1, "%d%c", &default_port, &null_byte);
-            if (n != 1 || default_port >= 0x10000)
+            int scanned = sscanf(str.c_str()+p+1, "%d%c", &default_port, &null_byte);
+            if (scanned != 1 || default_port >= 0x10000)
                 return false;
             str = str.substr(0, p);
         }
diff --git a/src/cli_alloc_osd.cpp b/src/cli_alloc_osd.cpp
index 67433a89..05380647 100644
--- a/src/cli_alloc_osd.cpp
+++ b/src/cli_alloc_osd.cpp
@@ -77,8 +77,8 @@ struct alloc_osd_t
                     std::string key = base64_decode(kv["key"].string_value());
                     osd_num_t cur_osd;
                     char null_byte = 0;
-                    sscanf(key.c_str() + parent->cli->st_cli.etcd_prefix.length(), "/osd/stats/%lu%c", &cur_osd, &null_byte);
-                    if (!cur_osd || null_byte != 0)
+                    int scanned = sscanf(key.c_str() + parent->cli->st_cli.etcd_prefix.length(), "/osd/stats/%lu%c", &cur_osd, &null_byte);
+                    if (scanned != 1 || !cur_osd)
                     {
                         fprintf(stderr, "Invalid key in etcd: %s\n", key.c_str());
                         continue;
diff --git a/src/cli_df.cpp b/src/cli_df.cpp
index 522790f2..4f8cf760 100644
--- a/src/cli_df.cpp
+++ b/src/cli_df.cpp
@@ -67,8 +67,8 @@ resume_1:
             // pool ID
             pool_id_t pool_id;
             char null_byte = 0;
-            sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/pool/stats/%u%c", &pool_id, &null_byte);
-            if (!pool_id || pool_id >= POOL_ID_MAX || null_byte != 0)
+            int scanned = sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/pool/stats/%u%c", &pool_id, &null_byte);
+            if (scanned != 1 || !pool_id || pool_id >= POOL_ID_MAX)
             {
                 fprintf(stderr, "Invalid key in etcd: %s\n", kv.key.c_str());
                 continue;
@@ -82,8 +82,8 @@ resume_1:
             // osd ID
             osd_num_t osd_num;
             char null_byte = 0;
-            sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/osd/stats/%lu%c", &osd_num, &null_byte);
-            if (!osd_num || osd_num >= POOL_ID_MAX || null_byte != 0)
+            int scanned = sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/osd/stats/%lu%c", &osd_num, &null_byte);
+            if (scanned != 1 || !osd_num || osd_num >= POOL_ID_MAX)
             {
                 fprintf(stderr, "Invalid key in etcd: %s\n", kv.key.c_str());
                 continue;
diff --git a/src/cli_ls.cpp b/src/cli_ls.cpp
index de60109e..aeb8b9c6 100644
--- a/src/cli_ls.cpp
+++ b/src/cli_ls.cpp
@@ -133,8 +133,8 @@ resume_1:
             // pool ID
             pool_id_t pool_id;
             char null_byte = 0;
-            sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/pool/stats/%u%c", &pool_id, &null_byte);
-            if (!pool_id || pool_id >= POOL_ID_MAX || null_byte != 0)
+            int scanned = sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(), "/pool/stats/%u%c", &pool_id, &null_byte);
+            if (scanned != 1 || !pool_id || pool_id >= POOL_ID_MAX)
             {
                 fprintf(stderr, "Invalid key in etcd: %s\n", kv.key.c_str());
                 continue;
@@ -149,9 +149,9 @@ resume_1:
             pool_id_t pool_id;
             inode_t only_inode_num;
             char null_byte = 0;
-            sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(),
+            int scanned = sscanf(kv.key.substr(parent->cli->st_cli.etcd_prefix.length()).c_str(),
                 "/inode/stats/%u/%lu%c", &pool_id, &only_inode_num, &null_byte);
-            if (!pool_id || pool_id >= POOL_ID_MAX || INODE_POOL(only_inode_num) != 0 || null_byte != 0)
+            if (scanned != 2 || !pool_id || pool_id >= POOL_ID_MAX || INODE_POOL(only_inode_num) != 0)
             {
                 fprintf(stderr, "Invalid key in etcd: %s\n", kv.key.c_str());
                 continue;
diff --git a/src/cli_rm.cpp b/src/cli_rm.cpp
index d85e0c7e..880c2606 100644
--- a/src/cli_rm.cpp
+++ b/src/cli_rm.cpp
@@ -384,8 +384,8 @@ resume_100:
                 pool_id_t pool_id = 0;
                 inode_t inode = 0;
                 char null_byte = 0;
-                sscanf(kv.key.c_str() + parent->cli->st_cli.etcd_prefix.length()+13, "%u/%lu%c", &pool_id, &inode, &null_byte);
-                if (!inode || null_byte != 0)
+                int scanned = sscanf(kv.key.c_str() + parent->cli->st_cli.etcd_prefix.length()+13, "%u/%lu%c", &pool_id, &inode, &null_byte);
+                if (scanned != 2 || !inode)
                 {
                     result = (cli_result_t){ .err = EIO, .text = "Bad key returned from etcd: "+kv.key };
                     state = 100;
diff --git a/src/cli_status.cpp b/src/cli_status.cpp
index fb32644b..d377ad73 100644
--- a/src/cli_status.cpp
+++ b/src/cli_status.cpp
@@ -132,8 +132,8 @@ resume_2:
             auto kv = parent->cli->st_cli.parse_etcd_kv(osd_stats[i]);
             osd_num_t stat_osd_num = 0;
             char null_byte = 0;
-            sscanf(kv.key.c_str() + parent->cli->st_cli.etcd_prefix.size(), "/osd/stats/%lu%c", &stat_osd_num, &null_byte);
-            if (!stat_osd_num || null_byte != 0)
+            int scanned = sscanf(kv.key.c_str() + parent->cli->st_cli.etcd_prefix.size(), "/osd/stats/%lu%c", &stat_osd_num, &null_byte);
+            if (scanned != 1 || !stat_osd_num)
             {
                 fprintf(stderr, "Invalid key in etcd: %s\n", kv.key.c_str());
                 continue;
diff --git a/src/etcd_state_client.cpp b/src/etcd_state_client.cpp
index 925a6934..4a456f44 100644
--- a/src/etcd_state_client.cpp
+++ b/src/etcd_state_client.cpp
@@ -684,8 +684,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
             // ID
             pool_id_t pool_id;
             char null_byte = 0;
-            sscanf(pool_item.first.c_str(), "%u%c", &pool_id, &null_byte);
-            if (!pool_id || pool_id >= POOL_ID_MAX || null_byte != 0)
+            int scanned = sscanf(pool_item.first.c_str(), "%u%c", &pool_id, &null_byte);
+            if (scanned != 1 || !pool_id || pool_id >= POOL_ID_MAX)
             {
                 fprintf(stderr, "Pool ID %s is invalid (must be a number less than 0x%x), skipping pool\n", pool_item.first.c_str(), POOL_ID_MAX);
                 continue;
@@ -829,8 +829,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
         {
             pool_id_t pool_id;
             char null_byte = 0;
-            sscanf(pool_item.first.c_str(), "%u%c", &pool_id, &null_byte);
-            if (!pool_id || pool_id >= POOL_ID_MAX || null_byte != 0)
+            int scanned = sscanf(pool_item.first.c_str(), "%u%c", &pool_id, &null_byte);
+            if (scanned != 1 || !pool_id || pool_id >= POOL_ID_MAX)
             {
                 fprintf(stderr, "Pool ID %s is invalid in PG configuration (must be a number less than 0x%x), skipping pool\n", pool_item.first.c_str(), POOL_ID_MAX);
                 continue;
@@ -838,8 +838,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
             for (auto & pg_item: pool_item.second.object_items())
             {
                 pg_num_t pg_num = 0;
-                sscanf(pg_item.first.c_str(), "%u%c", &pg_num, &null_byte);
-                if (!pg_num || null_byte != 0)
+                int scanned = sscanf(pg_item.first.c_str(), "%u%c", &pg_num, &null_byte);
+                if (scanned != 1 || !pg_num)
                 {
                     fprintf(stderr, "Bad key in pool %u PG configuration: %s (must be a number), skipped\n", pool_id, pg_item.first.c_str());
                     continue;
@@ -889,8 +889,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
         pool_id_t pool_id = 0;
         pg_num_t pg_num = 0;
         char null_byte = 0;
-        sscanf(key.c_str() + etcd_prefix.length()+12, "%u/%u%c", &pool_id, &pg_num, &null_byte);
-        if (!pool_id || pool_id >= POOL_ID_MAX || !pg_num || null_byte != 0)
+        int scanned = sscanf(key.c_str() + etcd_prefix.length()+12, "%u/%u%c", &pool_id, &pg_num, &null_byte);
+        if (scanned != 2 || !pool_id || pool_id >= POOL_ID_MAX || !pg_num)
         {
             fprintf(stderr, "Bad etcd key %s, ignoring\n", key.c_str());
         }
@@ -944,8 +944,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
         pool_id_t pool_id = 0;
         pg_num_t pg_num = 0;
         char null_byte = 0;
-        sscanf(key.c_str() + etcd_prefix.length()+10, "%u/%u%c", &pool_id, &pg_num, &null_byte);
-        if (!pool_id || pool_id >= POOL_ID_MAX || !pg_num || null_byte != 0)
+        int scanned = sscanf(key.c_str() + etcd_prefix.length()+10, "%u/%u%c", &pool_id, &pg_num, &null_byte);
+        if (scanned != 2 || !pool_id || pool_id >= POOL_ID_MAX || !pg_num)
         {
             fprintf(stderr, "Bad etcd key %s, ignoring\n", key.c_str());
         }
@@ -1015,8 +1015,8 @@ void etcd_state_client_t::parse_state(const etcd_kv_t & kv)
         uint64_t pool_id = 0;
         uint64_t inode_num = 0;
         char null_byte = 0;
-        sscanf(key.c_str() + etcd_prefix.length()+14, "%lu/%lu%c", &pool_id, &inode_num, &null_byte);
-        if (!pool_id || pool_id >= POOL_ID_MAX || !inode_num || (inode_num >> (64-POOL_ID_BITS)) || null_byte != 0)
+        int scanned = sscanf(key.c_str() + etcd_prefix.length()+14, "%lu/%lu%c", &pool_id, &inode_num, &null_byte);
+        if (scanned != 2 || !pool_id || pool_id >= POOL_ID_MAX || !inode_num || (inode_num >> (64-POOL_ID_BITS)))
         {
             fprintf(stderr, "Bad etcd key %s, ignoring\n", key.c_str());
         }
diff --git a/src/msgr_rdma.cpp b/src/msgr_rdma.cpp
index 8e63195f..d39105de 100644
--- a/src/msgr_rdma.cpp
+++ b/src/msgr_rdma.cpp
@@ -19,12 +19,12 @@ std::string msgr_rdma_address_t::to_string()
 bool msgr_rdma_address_t::from_string(const char *str, msgr_rdma_address_t *dest)
 {
     uint64_t* gid = (uint64_t*)&dest->gid;
-    int n = sscanf(
+    int scanned = sscanf(
         str, "%hx:%x:%x:%16lx%16lx", &dest->lid, &dest->qpn, &dest->psn, gid, gid+1
     );
     gid[0] = be64toh(gid[0]);
     gid[1] = be64toh(gid[1]);
-    return n == 5;
+    return scanned == 5;
 }
 
 msgr_rdma_context_t::~msgr_rdma_context_t()
diff --git a/src/nfs_proxy.cpp b/src/nfs_proxy.cpp
index 26c643e2..a0c3bb53 100644
--- a/src/nfs_proxy.cpp
+++ b/src/nfs_proxy.cpp
@@ -346,8 +346,8 @@ void nfs_proxy_t::parse_stats(etcd_kv_t & kv)
         pool_id_t pool_id = 0;
         inode_t inode_num = 0;
         char null_byte = 0;
-        sscanf(key.c_str() + cli->st_cli.etcd_prefix.length()+13, "%u/%lu%c", &pool_id, &inode_num, &null_byte);
-        if (!pool_id || pool_id >= POOL_ID_MAX || !inode_num || null_byte != 0)
+        int scanned = sscanf(key.c_str() + cli->st_cli.etcd_prefix.length()+13, "%u/%lu%c", &pool_id, &inode_num, &null_byte);
+        if (scanned != 2 || !pool_id || pool_id >= POOL_ID_MAX || !inode_num)
         {
             fprintf(stderr, "Bad etcd key %s, ignoring\n", key.c_str());
         }
@@ -360,8 +360,8 @@ void nfs_proxy_t::parse_stats(etcd_kv_t & kv)
     {
         pool_id_t pool_id = 0;
         char null_byte = 0;
-        sscanf(key.c_str() + cli->st_cli.etcd_prefix.length()+12, "%u%c", &pool_id, &null_byte);
-        if (!pool_id || pool_id >= POOL_ID_MAX)
+        int scanned = sscanf(key.c_str() + cli->st_cli.etcd_prefix.length()+12, "%u%c", &pool_id, &null_byte);
+        if (scanned != 1 || !pool_id || pool_id >= POOL_ID_MAX)
         {
             fprintf(stderr, "Bad etcd key %s, ignoring\n", key.c_str());
         }
diff --git a/src/osd_cluster.cpp b/src/osd_cluster.cpp
index eb30ef12..fb4a19d8 100644
--- a/src/osd_cluster.cpp
+++ b/src/osd_cluster.cpp
@@ -967,8 +967,8 @@ void osd_t::report_pg_states()
                         pool_id_t pool_id = 0;
                         pg_num_t pg_num = 0;
                         char null_byte = 0;
-                        sscanf(kv.key.c_str() + st_cli.etcd_prefix.length()+10, "%u/%u%c", &pool_id, &pg_num, &null_byte);
-                        if (null_byte == 0)
+                        int scanned = sscanf(kv.key.c_str() + st_cli.etcd_prefix.length()+10, "%u/%u%c", &pool_id, &pg_num, &null_byte);
+                        if (scanned == 2)
                         {
                             auto pg_it = pgs.find({ .pool_id = pool_id, .pg_num = pg_num });
                             if (pg_it != pgs.end() && pg_it->second.state != PG_OFFLINE && pg_it->second.state != PG_STARTING &&