diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index a68ded0e2..a45dc26b9 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -1226,14 +1226,15 @@ void CheckIO::checkFormatString(const Token * const tok,
                                 done = true;
                                 break;
                             case 'h': // Can be 'hh' (signed char or unsigned char) or 'h' (short int or unsigned short int)
-                            case 'l': // Can be 'll' (long long int or unsigned long long int) or 'l' (long int or unsigned long int)
+                            case 'l': { // Can be 'll' (long long int or unsigned long long int) or 'l' (long int or unsigned long int)
                                 // If the next character is the same (which makes 'hh' or 'll') then expect another alphabetical character
-                                if (i != formatString.end() && *(i+1) == *i) {
-                                    if (i+1 != formatString.end()) {
-                                        if (!isalpha(*(i+2))) {
+                                const bool isSecondCharAvailable = ((i + 1) != formatString.end());
+                                if (i != formatString.end() && isSecondCharAvailable && *(i + 1) == *i) {
+                                    if (isSecondCharAvailable) {
+                                        if (!isalpha(*(i + 2))) {
                                             std::string modifier;
                                             modifier += *i;
-                                            modifier += *(i+1);
+                                            modifier += *(i + 1);
                                             invalidLengthModifierError(tok, numFormat, modifier);
                                             done = true;
                                         } else {
@@ -1245,7 +1246,7 @@ void CheckIO::checkFormatString(const Token * const tok,
                                     }
                                 } else {
                                     if (i != formatString.end()) {
-                                        if (!isalpha(*(i+1))) {
+                                        if ((i + 1) != formatString.end() && !isalpha(*(i + 1))) {
                                             std::string modifier;
                                             modifier += *i;
                                             invalidLengthModifierError(tok, numFormat, modifier);
@@ -1257,7 +1258,8 @@ void CheckIO::checkFormatString(const Token * const tok,
                                         done = true;
                                     }
                                 }
-                                break;
+                            }
+                            break;
                             case 'I': // Microsoft extension: I for size_t and ptrdiff_t, I32 for __int32, and I64 for __int64
                                 if ((*(i+1) == '3' && *(i+2) == '2') ||
                                     (*(i+1) == '6' && *(i+2) == '4')) {
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index 77df74a73..22df7c1ff 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -92,7 +92,8 @@ void memleak_mmap(int fd)
     // cppcheck-suppress memleak
 }
 
-void resourceLeak_fdopen(int fd) {
+void resourceLeak_fdopen(int fd)
+{
     // cppcheck-suppress unreadVariable
     FILE *f = fdopen(fd, "r");
     // cppcheck-suppress resourceLeak