diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index 601d33f72..a9d6648cf 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -363,6 +363,25 @@ MathLib::bigint MathLib::toLongNumber(const std::string & str)
             return static_cast<bigint>(doubleval);
     }
 
+    if (str[0] == '\'' && str.size() >= 3U && str[str.size()-1U] == '\'') {
+        char c;
+        if (str.size() == 3U &&
+            str[0] == '\'' &&
+            str[2] == '\'')
+            c = str[1];
+        else if (str == "\'\\0\'")
+            c = '\0';
+        else if (str == "\'\\n\'")
+            c = '\n';
+        else if (str == "\'\\r\'")
+            c = '\r';
+        else if (str == "\'\\t\'")
+            c = '\t';
+        else
+            throw InternalError(0, "MathLib::toLongNumber: Unhandled char constant " + str);
+        return c & 0xff;
+    }
+
     bigint ret = 0;
     std::istringstream istr(str);
     istr >> ret;
diff --git a/lib/templatesimplifier.cpp b/lib/templatesimplifier.cpp
index 185d1b14e..b6ca17460 100644
--- a/lib/templatesimplifier.cpp
+++ b/lib/templatesimplifier.cpp
@@ -1023,7 +1023,8 @@ bool TemplateSimplifier::simplifyCalculations(Token *_tokens)
         }
 
         if (Token::Match(tok->previous(), "(|&&|%oror% %char% %comp% %num% &&|%oror%|)")) {
-            tok->str(MathLib::toString(tok->str()[1] & 0xff));
+            int c = MathLib::toLongNumber(tok->str());
+            tok->str(MathLib::toString(c));
         }
 
         if (tok->isNumber()) {
diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 2e1918f44..7f71dfed3 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -594,29 +594,10 @@ static void setTokenValue(Token* tok, const ValueFlow::Value &value)
 static void valueFlowNumber(TokenList *tokenlist)
 {
     for (Token *tok = tokenlist->front(); tok; tok = tok->next()) {
-        if (tok->isNumber() && MathLib::isInt(tok->str())) {
+        if ((tok->isNumber() && MathLib::isInt(tok->str())) || (tok->tokType() == Token::eChar)) {
             ValueFlow::Value value(MathLib::toLongNumber(tok->str()));
             value.setKnown();
             setTokenValue(tok, value);
-        } else if (tok->tokType() == Token::eChar) {
-            char c;
-            if (tok->str() == "\'\\n\'")
-                c = '\n';
-            else if (tok->str() == "\'\\r\'")
-                c = '\r';
-            else if (tok->str() == "\'\\t\'")
-                c = '\t';
-            else if (tok->str().size() == 3U &&
-                     tok->str()[0] == '\'' &&
-                     (tok->str()[1] & 0x80) == 0 &&
-                     tok->str()[2] == '\'')
-                c = tok->str()[1];
-            else
-                continue;
-
-            ValueFlow::Value value(c);
-            value.setKnown();
-            setTokenValue(tok, value);
         }
     }
 
diff --git a/test/testobsolescentfunctions.cpp b/test/testobsolescentfunctions.cpp
index 4911911c8..f14ab07ba 100644
--- a/test/testobsolescentfunctions.cpp
+++ b/test/testobsolescentfunctions.cpp
@@ -104,7 +104,7 @@ private:
         check("void f()\n"
               "{\n"
               "    struct hostent *hp;\n"
-              "    if(!hp = gethostbyname('127.0.0.1')) {\n"
+              "    if(!hp = gethostbyname(\"127.0.0.1\")) {\n"
               "        exit(1);\n"
               "    }\n"
               "}");
@@ -115,7 +115,7 @@ private:
         check("void f()\n"
               "{\n"
               "    long addr;\n"
-              "    addr = inet_addr('127.0.0.1');\n"
+              "    addr = inet_addr(\"127.0.0.1\");\n"
               "    if(!hp = gethostbyaddr((char *) &addr, sizeof(addr), AF_INET)) {\n"
               "        exit(1);\n"
               "    }\n"
@@ -164,7 +164,7 @@ private:
 
         check("const char f()\n"
               "{\n"
-              "    const char var[6] = 'index';\n"
+              "    const char var[6] = \"index\";\n"
               "    const char i = index(var, 0);\n"
               "    return i;\n"
               "}");
@@ -188,7 +188,7 @@ private:
 
         check("void f()\n"
               "{\n"
-              "    const char var[7] = 'rindex';\n"
+              "    const char var[7] = \"rindex\";\n"
               "    print(rindex(var, 0));\n"
               "}");
         ASSERT_EQUALS("[test.cpp:4]: (style) Obsolete function 'rindex' called. It is recommended to use the function 'strrchr' instead.\n", errout.str());
diff --git a/test/teststring.cpp b/test/teststring.cpp
index ff432d8f9..28404351e 100644
--- a/test/teststring.cpp
+++ b/test/teststring.cpp
@@ -307,10 +307,10 @@ private:
 
         // Ticket #5734
         check("int foo(char c) {\n"
-              "return c == '42';}", "test.cpp");
+              "return c == '4';}", "test.cpp");
         ASSERT_EQUALS("", errout.str());
         check("int foo(char c) {\n"
-              "return c == '42';}", "test.c");
+              "return c == '4';}", "test.c");
         ASSERT_EQUALS("", errout.str());
         check("int foo(char c) {\n"
               "return c == \"42\"[0];}", "test.cpp");