diff --git a/cli/threadexecutor.cpp b/cli/threadexecutor.cpp
index f1dd97aa5..1ec7dbc17 100644
--- a/cli/threadexecutor.cpp
+++ b/cli/threadexecutor.cpp
@@ -110,7 +110,7 @@ int ThreadExecutor::handleRead(unsigned int &result)
         unsigned int fileResult = 0;
         iss >> fileResult;
         result += fileResult;
-        _errorLogger.reportStatus(_fileCount, _filenames.size());
+        _errorLogger.reportStatus(_fileCount, (unsigned int)_filenames.size());
         delete [] buf;
         return -1;
     }
@@ -216,7 +216,7 @@ unsigned int ThreadExecutor::check()
 
 void ThreadExecutor::writeToPipe(char type, const std::string &data)
 {
-    unsigned int len = data.length() + 1;
+    std::size_t len = data.length() + 1;
     char *out = new char[ len + 1 + sizeof(len)];
     out[0] = type;
     std::memcpy(&(out[1]), &len, sizeof(len));
diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index de4ce3bb0..8bb441f97 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -813,7 +813,7 @@ void CheckBufferOverrun::checkScope(const Token *tok, const std::vector<std::str
             (varid == 0 && Token::Match(tok, ("strcpy|strcat ( " + varnames + " , %str% )").c_str())))
         {
             const std::size_t len = Token::getStrLength(tok->tokAt(varc + 4));
-            if (total_size > 0 && len >= total_size)
+            if (total_size > 0 && len >= (unsigned int)total_size)
             {
                 bufferOverrun(tok, varid > 0 ? "" : varnames.c_str());
                 continue;
@@ -1071,7 +1071,7 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
         if (Token::Match(tok, "strcpy|strcat ( %varid% , %str% )", arrayInfo.varid))
         {
             const std::size_t len = Token::getStrLength(tok->tokAt(4));
-            if (total_size > 0 && len >= total_size)
+            if (total_size > 0 && len >= (unsigned int)total_size)
             {
                 bufferOverrun(tok, arrayInfo.varname);
                 continue;
@@ -1087,7 +1087,7 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
             while (tok2 && Token::Match(tok2, "strcat ( %varid% , %str% ) ;", arrayInfo.varid))
             {
                 charactersAppend += Token::getStrLength(tok2->tokAt(4));
-                if (charactersAppend >= total_size)
+                if (charactersAppend >= (unsigned int)total_size)
                 {
                     bufferOverrun(tok2, arrayInfo.varname);
                     break;
@@ -1542,7 +1542,7 @@ MathLib::bigint CheckBufferOverrun::countSprintfLength(const std::string &input_
         }
     }
 
-    return input_string_size;
+    return (MathLib::bigint)input_string_size;
 }
 
 void CheckBufferOverrun::checkSprintfCall(const Token *tok, const MathLib::bigint size)
diff --git a/lib/checkuninitvar.cpp b/lib/checkuninitvar.cpp
index 58f43decb..734300a4e 100644
--- a/lib/checkuninitvar.cpp
+++ b/lib/checkuninitvar.cpp
@@ -625,7 +625,7 @@ private:
                 {
                     if (Token::Match(tok.tokAt(6), "%num% )"))
                     {
-                        const unsigned int len = Token::getStrLength(tok.tokAt(4));
+                        const std::size_t len = Token::getStrLength(tok.tokAt(4));
                         const MathLib::bigint sz = MathLib::toLongNumber(tok.strAt(6));
                         if (sz >= 0 && len >= static_cast<unsigned long>(sz))
                         {
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index c60219743..925f1d26a 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -2324,7 +2324,7 @@ void Tokenizer::arraySize()
         else if (Token::Match(tok, "%var% [ ] = %str% ;"))
         {
             std::size_t sz = tok->strAt(4).length() - 1;
-            tok->next()->insertToken(MathLib::toString<unsigned int>(sz));
+            tok->next()->insertToken(MathLib::toString<unsigned int>((unsigned int)sz));
         }
     }
 }
@@ -8125,7 +8125,7 @@ std::string Tokenizer::simplifyString(const std::string &source)
                 // We will replace all other character as 'a'
                 // If that causes problems in the future, this can
                 // be improved. But for now, this should be OK.
-                unsigned char n = 1;
+                unsigned int n = 1;
                 while (n < 2 && std::isxdigit(str[i+1+n]))
                     ++n;
                 --i;