diff --git a/src/pem.c b/src/pem.c
index 9059477e..2e68c74d 100644
--- a/src/pem.c
+++ b/src/pem.c
@@ -67,6 +67,8 @@ _libssh2_pem_parse(LIBSSH2_SESSION * session,
     int ret;
 
     do {
+        *line = '\0';
+
         if (readline(line, LINE_SIZE, fp)) {
             return -1;
         }
@@ -91,12 +93,18 @@ _libssh2_pem_parse(LIBSSH2_SESSION * session,
             b64datalen += linelen;
         }
 
+        *line = '\0';
+
         if (readline(line, LINE_SIZE, fp)) {
             ret = -1;
             goto out;
         }
     } while (strcmp(line, headerend) != 0);
 
+    if (!b64data) {
+        return -1;
+    }
+
     if (libssh2_base64_decode(session, (char**) data, datalen,
                               b64data, b64datalen)) {
         ret = -1;