diff --git a/src/curl.cpp b/src/curl.cpp
index f1bd996..255ea66 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -2355,7 +2355,7 @@ int S3fsCurl::RequestPerform(bool dontAddAuthHeaders /*=false*/)
             case CURLE_PEER_FAILED_VERIFICATION:
                 S3FS_PRN_ERR("### CURLE_PEER_FAILED_VERIFICATION");
 
-                first_pos = bucket.find_first_of(".");
+                first_pos = bucket.find_first_of('.');
                 if(first_pos != std::string::npos){
                     S3FS_PRN_INFO("curl returned a CURL_PEER_FAILED_VERIFICATION error");
                     S3FS_PRN_INFO("security issue found: buckets with periods in their name are incompatible with http");
diff --git a/src/s3fs.cpp b/src/s3fs.cpp
index 9002abb..107c2a1 100644
--- a/src/s3fs.cpp
+++ b/src/s3fs.cpp
@@ -3502,7 +3502,7 @@ static int parse_passwd_file(bucketkvmap_t& resmap)
     // read '=' type
     kvmap_t kv;
     for(iter = linelist.begin(); iter != linelist.end(); ++iter){
-        first_pos = iter->find_first_of("=");
+        first_pos = iter->find_first_of('=');
         if(first_pos == std::string::npos){
             continue;
         }
@@ -3523,8 +3523,8 @@ static int parse_passwd_file(bucketkvmap_t& resmap)
 
     // read ':' type
     for(iter = linelist.begin(); iter != linelist.end(); ++iter){
-        first_pos       = iter->find_first_of(":");
-        size_t last_pos = iter->find_last_of(":");
+        first_pos       = iter->find_first_of(':');
+        size_t last_pos = iter->find_last_of(':');
         if(first_pos == std::string::npos){
             continue;
         }
@@ -4932,7 +4932,7 @@ int main(int argc, char* argv[])
     // See issue #128strncasecmp
     /* 
     if(1 == S3fsCurl::GetSslVerifyHostname()){
-        found = bucket.find_first_of(".");
+        found = bucket.find_first_of('.');
         if(found != std::string::npos){
             found = s3host.find("https:");
             if(found != std::string::npos){