diff --git a/cli/cmdlineparser.cpp b/cli/cmdlineparser.cpp
index b35a411e3..6ef6b578f 100644
--- a/cli/cmdlineparser.cpp
+++ b/cli/cmdlineparser.cpp
@@ -25,6 +25,7 @@
 #include "timer.h"
 #include "settings.h"
 #include "cmdlineparser.h"
+#include "path.h"
 
 // xml is used in rules
 #include "tinyxml/tinyxml.h"
@@ -254,9 +255,10 @@ bool CmdLineParser::ParseFromArgs(int argc, const char* const argv[])
             {
                 path = 2 + argv[i];
             }
+            path = Path::fromNativeSeparators(path);
 
             // If path doesn't end with / or \, add it
-            if (path[path.length()-1] != '/' && path[path.length()-1] != '\\')
+            if (path[path.length()-1] != '/')
                 path += '/';
 
             _settings->_includePaths.push_back(path);
diff --git a/cli/cppcheckexecutor.cpp b/cli/cppcheckexecutor.cpp
index 661c1a9ab..c4d5b9f97 100644
--- a/cli/cppcheckexecutor.cpp
+++ b/cli/cppcheckexecutor.cpp
@@ -24,6 +24,7 @@
 #include <cstdlib> // EXIT_SUCCESS and EXIT_FAILURE
 #include "cmdlineparser.h"
 #include "filelister.h"
+#include "path.h"
 
 CppCheckExecutor::CppCheckExecutor()
 {
@@ -63,9 +64,10 @@ bool CppCheckExecutor::parseFromArgs(CppCheck *cppcheck, int argc, const char* c
              iter != _settings._includePaths.end();
              ++iter)
         {
-            if (!getFileLister()->isDirectory(iter->c_str()))
+            const std::string path(Path::toNativeSeparators(*iter));
+            if (!getFileLister()->isDirectory(path.c_str()))
             {
-                std::cout << "cppcheck: error: Couldn't find path given by -I '" + *iter + "'" << std::endl;
+                std::cout << "cppcheck: error: Couldn't find path given by -I '" + path + "'" << std::endl;
                 return false;
             }
         }
diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 5f5b4ff44..467ad7f58 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -1537,10 +1537,11 @@ void Preprocessor::handleIncludes(std::string &code, const std::string &filePath
             includePaths2.push_front("");
             for (std::list<std::string>::const_iterator iter = includePaths2.begin(); iter != includePaths2.end(); ++iter)
             {
-                fin.open((*iter + filename).c_str());
+                const std::string path(Path::toNativeSeparators(*iter));
+                fin.open((path + filename).c_str());
                 if (fin.is_open())
                 {
-                    filename = *iter + filename;
+                    filename = path + filename;
                     fileOpened = true;
                     break;
                 }
diff --git a/test/testcmdlineparser.cpp b/test/testcmdlineparser.cpp
index 6d45d09bb..3caba1749 100644
--- a/test/testcmdlineparser.cpp
+++ b/test/testcmdlineparser.cpp
@@ -51,6 +51,9 @@ private:
         TEST_CASE(defines3);
         TEST_CASE(includesnopath);
         TEST_CASE(includes);
+        TEST_CASE(includesslash);
+        TEST_CASE(includesbackslash);
+        TEST_CASE(includesnospace);
         TEST_CASE(includes2);
         TEST_CASE(enabledAll);
         TEST_CASE(enabledStyle);
@@ -276,6 +279,36 @@ private:
         ASSERT_EQUALS(" include/", settings._includePaths.front());
     }
 
+    void includesslash()
+    {
+        REDIRECT;
+        const char *argv[] = {"cppcheck", "-I include/", "file.cpp"};
+        Settings settings;
+        CmdLineParser parser(&settings);
+        ASSERT(parser.ParseFromArgs(3, argv));
+        ASSERT_EQUALS(" include/", settings._includePaths.front());
+    }
+
+    void includesbackslash()
+    {
+        REDIRECT;
+        const char *argv[] = {"cppcheck", "-I include\\", "file.cpp"};
+        Settings settings;
+        CmdLineParser parser(&settings);
+        ASSERT(parser.ParseFromArgs(3, argv));
+        ASSERT_EQUALS(" include/", settings._includePaths.front());
+    }
+
+    void includesnospace()
+    {
+        REDIRECT;
+        const char *argv[] = {"cppcheck", "-Iinclude", "file.cpp"};
+        Settings settings;
+        CmdLineParser parser(&settings);
+        ASSERT(parser.ParseFromArgs(3, argv));
+        ASSERT_EQUALS("include/", settings._includePaths.front());
+    }
+
     void includes2()
     {
         REDIRECT;