diff --git a/src/bitcoin-tx.cpp b/src/bitcoin-tx.cpp
--- a/src/bitcoin-tx.cpp
+++ b/src/bitcoin-tx.cpp
@@ -334,7 +334,7 @@
     bool bScriptHash = false;
     if (vStrInputParts.size() == 3) {
         std::string flags = vStrInputParts[2];
-        bScriptHash = (flags.find("S") != std::string::npos);
+        bScriptHash = (flags.find('S') != std::string::npos);
     }
 
     if (bScriptHash) {
@@ -395,7 +395,7 @@
     bool bScriptHash = false;
     if (vStrInputParts.size() == numkeys + 4) {
         std::string flags = vStrInputParts.back();
-        bScriptHash = (flags.find("S") != std::string::npos);
+        bScriptHash = (flags.find('S') != std::string::npos);
     } else if (vStrInputParts.size() > numkeys + 4) {
         // Validate that there were no more parameters passed
         throw std::runtime_error("Too many parameters");
@@ -462,7 +462,7 @@
     bool bScriptHash = false;
     if (vStrInputParts.size() == 3) {
         std::string flags = vStrInputParts.back();
-        bScriptHash = (flags.find("S") != std::string::npos);
+        bScriptHash = (flags.find('S') != std::string::npos);
     }
 
     if (bScriptHash) {
diff --git a/src/httprpc.cpp b/src/httprpc.cpp
--- a/src/httprpc.cpp
+++ b/src/httprpc.cpp
@@ -86,11 +86,11 @@
  * config file.
  */
 static bool multiUserAuthorized(std::string strUserPass) {
-    if (strUserPass.find(":") == std::string::npos) {
+    if (strUserPass.find(':') == std::string::npos) {
         return false;
     }
-    std::string strUser = strUserPass.substr(0, strUserPass.find(":"));
-    std::string strPass = strUserPass.substr(strUserPass.find(":") + 1);
+    std::string strUser = strUserPass.substr(0, strUserPass.find(':'));
+    std::string strPass = strUserPass.substr(strUserPass.find(':') + 1);
 
     for (const std::string &strRPCAuth : gArgs.GetArgs("-rpcauth")) {
         // Search for multi-user login/pass "rpcauth" from config
@@ -142,8 +142,8 @@
     boost::trim(strUserPass64);
     std::string strUserPass = DecodeBase64(strUserPass64);
 
-    if (strUserPass.find(":") != std::string::npos) {
-        strAuthUsernameOut = strUserPass.substr(0, strUserPass.find(":"));
+    if (strUserPass.find(':') != std::string::npos) {
+        strAuthUsernameOut = strUserPass.substr(0, strUserPass.find(':'));
     }
 
     // Check if authorized under single-user field
diff --git a/src/rest.cpp b/src/rest.cpp
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -469,9 +469,9 @@
 
         for (size_t i = (fCheckMemPool) ? 1 : 0; i < uriParts.size(); i++) {
             int32_t nOutput;
-            std::string strTxid = uriParts[i].substr(0, uriParts[i].find("-"));
+            std::string strTxid = uriParts[i].substr(0, uriParts[i].find('-'));
             std::string strOutput =
-                uriParts[i].substr(uriParts[i].find("-") + 1);
+                uriParts[i].substr(uriParts[i].find('-') + 1);
 
             if (!ParseInt32(strOutput, &nOutput) || !IsHex(strTxid)) {
                 return RESTERR(req, HTTP_BAD_REQUEST, "Parse error");
diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -207,7 +207,7 @@
     UniValue params(UniValue::VOBJ);
 
     for (const std::string &s : strParams) {
-        size_t pos = s.find("=");
+        size_t pos = s.find('=');
         if (pos == std::string::npos) {
             throw(std::runtime_error("No '=' in named argument '" + s +
                                      "', this needs to be present for every "
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -650,7 +650,7 @@
     CNetAddr netAddr;
     bool isSubnet = false;
 
-    if (request.params[0].get_str().find("/") != std::string::npos) {
+    if (request.params[0].get_str().find('/') != std::string::npos) {
         isSubnet = true;
     }
 
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -614,7 +614,7 @@
         s >> nCreditDebit >> nTime >> LIMITED_STRING(strOtherAccount, 65536) >>
             LIMITED_STRING(strComment, 65536);
 
-        size_t nSepPos = strComment.find("\0", 0, 1);
+        size_t nSepPos = strComment.find('\0');
         mapValue.clear();
         if (std::string::npos != nSepPos) {
             CDataStream ss(std::vector<char>(strComment.begin() + nSepPos + 1,