diff --git a/src/linux.cc b/src/linux.cc
index 12532514..94498616 100644
--- a/src/linux.cc
+++ b/src/linux.cc
@@ -1014,7 +1014,7 @@ int update_stat(void) {
 
       cpu[idx].cpu_last_total = cpu[idx].cpu_total;
       cpu[idx].cpu_last_active_total = cpu[idx].cpu_active_total;
-      for (i = samples - 1; i > 0; i--) {
+      for (i = samples - 1; i > 0 && i < CPU_SAMPLE_COUNT; i--) {
         cpu[idx].cpu_val[i] = cpu[idx].cpu_val[i - 1];
       }
     }
diff --git a/src/mail.cc b/src/mail.cc
index 22eaf276..138c312e 100644
--- a/src/mail.cc
+++ b/src/mail.cc
@@ -814,7 +814,10 @@ void imap_cb::work() {
           }
           if (buf != nullptr) {
             // back up until we reach '*'
-            while (buf >= recvbuf && buf[0] != '*') { buf--; }
+            while (buf >= recvbuf && buf < (recvbuf + MAXDATASIZE) - 1 &&
+                   buf[0] != '*') {
+              buf--;
+            }
             if (sscanf(buf, "* %lu EXISTS\r\n", &messages) == 1) {
               std::lock_guard<std::mutex> lock(result_mutex);
               if (result.messages != messages) {
@@ -831,7 +834,10 @@ void imap_cb::work() {
           }
           if (buf != nullptr) {
             // back up until we reach '*'
-            while (buf >= recvbuf && buf[0] != '*') { buf--; }
+            while (buf >= recvbuf && buf < (recvbuf + MAXDATASIZE) - 1 &&
+                   buf[0] != '*') {
+              buf--;
+            }
             if (sscanf(buf, "* %lu RECENT\r\n", &recent) != 1) { recent = 0; }
           }
         }