diff --git a/programs/msiexec/msiexec.c b/programs/msiexec/msiexec.c
index 6b6d9f08a67..a9184680637 100644
--- a/programs/msiexec/msiexec.c
+++ b/programs/msiexec/msiexec.c
@@ -110,6 +110,20 @@ static VOID StringCompareRemoveLast(LPSTR String, CHAR character)
 	if(len && String[len-1] == character) String[len-1] = 0;
 }
 
+static INT MSIEXEC_lstrncmpiA(LPCSTR str1, LPCSTR str2, INT size)
+{
+    INT ret;
+
+    if ((str1 == NULL) && (str2 == NULL)) return 0;
+    if (str1 == NULL) return -1;
+    if (str2 == NULL) return 1;
+
+    ret = CompareStringA(GetThreadLocale(), NORM_IGNORECASE, str1, size, str2, -1);
+    if (ret) ret -= 2;
+
+    return ret;
+}
+
 static VOID *LoadProc(LPCSTR DllName, LPCSTR ProcName, HMODULE* DllHandle)
 {
 	VOID* (*proc)(void);
@@ -212,15 +226,15 @@ int main(int argc, char *argv[])
 	{
 		WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 
-                if (!strcasecmp(argv[i], "/regserver"))
+                if (!lstrcmpiA(argv[i], "/regserver"))
                 {
                     FunctionRegServer = TRUE;
                 }
-                else if (!strcasecmp(argv[i], "/unregserver") || !strcasecmp(argv[i], "/unregister"))
+                else if (!lstrcmpiA(argv[i], "/unregserver") || !lstrcmpiA(argv[i], "/unregister"))
                 {
                     FunctionUnregServer = TRUE;
                 }
-		else if(!strncasecmp(argv[i], "/i", 2))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "/i", 2))
 		{
 			char *argvi = argv[i];
 			FunctionInstall = TRUE;
@@ -235,7 +249,7 @@ int main(int argc, char *argv[])
 			}
 			GotProductCode = GetProductCode(argvi, &PackageName, &ProductCode);
 		}
-		else if(!strcasecmp(argv[i], "/a"))
+		else if(!lstrcmpiA(argv[i], "/a"))
 		{
 			FunctionInstall = TRUE;
 			FunctionInstallAdmin = TRUE;
@@ -247,7 +261,7 @@ int main(int argc, char *argv[])
 			PackageName = argv[i];
 			StringListAppend(&Properties, ActionAdmin);
 		}
-		else if(!strncasecmp(argv[i], "/f", 2))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "/f", 2))
 		{
 			int j;
 			int len = strlen(argv[i]);
@@ -315,7 +329,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			GotProductCode = GetProductCode(argv[i], &PackageName, &ProductCode);
 		}
-		else if(!strcasecmp(argv[i], "/x"))
+		else if(!lstrcmpiA(argv[i], "/x"))
 		{
 			FunctionInstall = TRUE;
 			i++;
@@ -325,7 +339,7 @@ int main(int argc, char *argv[])
 			GotProductCode = GetProductCode(argv[i], &PackageName, &ProductCode);
 			StringListAppend(&Properties, RemoveAll);
 		}
-		else if(!strncasecmp(argv[i], "/j", 2))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "/j", 2))
 		{
 			int j;
 			int len = strlen(argv[i]);
@@ -353,7 +367,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			PackageName = argv[i];
 		}
-		else if(!strcasecmp(argv[i], "u"))
+		else if(!lstrcmpiA(argv[i], "u"))
 		{
 			FunctionAdvertise = TRUE;
 			AdvertiseMode = ADVERTISEFLAGS_USERASSIGN;
@@ -363,7 +377,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			PackageName = argv[i];
 		}
-		else if(!strcasecmp(argv[i], "m"))
+		else if(!lstrcmpiA(argv[i], "m"))
 		{
 			FunctionAdvertise = TRUE;
 			AdvertiseMode = ADVERTISEFLAGS_MACHINEASSIGN;
@@ -373,7 +387,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			PackageName = argv[i];
 		}
-		else if(!strcasecmp(argv[i], "/t"))
+		else if(!lstrcmpiA(argv[i], "/t"))
 		{
 			i++;
 			if(i >= argc)
@@ -382,12 +396,12 @@ int main(int argc, char *argv[])
 			StringListAppend(&Transforms, argv[i]);
 			StringListAppend(&Transforms, ";");
 		}
-		else if(!strncasecmp(argv[i], "TRANSFORMS=", 11))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "TRANSFORMS=", 11))
 		{
 			StringListAppend(&Transforms, argv[i]+11);
 			StringListAppend(&Transforms, ";");
 		}
-		else if(!strcasecmp(argv[i], "/g"))
+		else if(!lstrcmpiA(argv[i], "/g"))
 		{
 			i++;
 			if(i >= argc)
@@ -395,7 +409,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			Language = strtol(argv[i], NULL, 0);
 		}
-		else if(!strncasecmp(argv[i], "/l", 2))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "/l", 2))
 		{
 			int j;
 			int len = strlen(argv[i]);
@@ -485,7 +499,7 @@ int main(int argc, char *argv[])
 				ExitProcess(1);
 			}
 		}
-		else if(!strcasecmp(argv[i], "/p"))
+		else if(!lstrcmpiA(argv[i], "/p"))
 		{
 			FunctionPatch = TRUE;
 			i++;
@@ -494,37 +508,37 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			PatchFileName = argv[i];
 		}
-		else if(!strncasecmp(argv[i], "/q", 2))
+		else if(!MSIEXEC_lstrncmpiA(argv[i], "/q", 2))
 		{
-			if(strlen(argv[i]) == 2 || !strcasecmp(argv[i]+2, "n"))
+			if(strlen(argv[i]) == 2 || !lstrcmpiA(argv[i]+2, "n"))
 			{
 				InstallUILevel = INSTALLUILEVEL_NONE;
 			}
-			else if(!strcasecmp(argv[i]+2, "b"))
+			else if(!lstrcmpiA(argv[i]+2, "b"))
 			{
 				InstallUILevel = INSTALLUILEVEL_BASIC;
 			}
-			else if(!strcasecmp(argv[i]+2, "r"))
+			else if(!lstrcmpiA(argv[i]+2, "r"))
 			{
 				InstallUILevel = INSTALLUILEVEL_REDUCED;
 			}
-			else if(!strcasecmp(argv[i]+2, "f"))
+			else if(!lstrcmpiA(argv[i]+2, "f"))
 			{
 				InstallUILevel = INSTALLUILEVEL_FULL|INSTALLUILEVEL_ENDDIALOG;
 			}
-			else if(!strcasecmp(argv[i]+2, "n+"))
+			else if(!lstrcmpiA(argv[i]+2, "n+"))
 			{
 				InstallUILevel = INSTALLUILEVEL_NONE|INSTALLUILEVEL_ENDDIALOG;
 			}
-			else if(!strcasecmp(argv[i]+2, "b+"))
+			else if(!lstrcmpiA(argv[i]+2, "b+"))
 			{
 				InstallUILevel = INSTALLUILEVEL_BASIC|INSTALLUILEVEL_ENDDIALOG;
 			}
-			else if(!strcasecmp(argv[i]+2, "b-"))
+			else if(!lstrcmpiA(argv[i]+2, "b-"))
 			{
 				InstallUILevel = INSTALLUILEVEL_BASIC|INSTALLUILEVEL_PROGRESSONLY;
 			}
-			else if(!strcasecmp(argv[i]+2, "b+!"))
+			else if(!lstrcmpiA(argv[i]+2, "b+!"))
             		{
 				InstallUILevel = INSTALLUILEVEL_BASIC|INSTALLUILEVEL_ENDDIALOG;
 				WINE_FIXME("Unknown modifier: !\n");
@@ -540,7 +554,7 @@ int main(int argc, char *argv[])
 				ExitProcess(1);
 			}
 		}
-		else if(!strcasecmp(argv[i], "/y"))
+		else if(!lstrcmpiA(argv[i], "/y"))
 		{
 			FunctionDllRegisterServer = TRUE;
 			i++;
@@ -549,7 +563,7 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			DllName = argv[i];
 		}
-		else if(!strcasecmp(argv[i], "/z"))
+		else if(!lstrcmpiA(argv[i], "/z"))
 		{
 			FunctionDllUnregisterServer = TRUE;
 			i++;
@@ -558,16 +572,16 @@ int main(int argc, char *argv[])
 			WINE_TRACE("argv[%d] = %s\n", i, argv[i]);
 			DllName = argv[i];
 		}
-		else if(!strcasecmp(argv[i], "/h") || !strcasecmp(argv[i], "/?"))
+		else if(!lstrcmpiA(argv[i], "/h") || !lstrcmpiA(argv[i], "/?"))
 		{
 			ShowUsage(0);
 		}
-		else if(!strcasecmp(argv[i], "/m"))
+		else if(!lstrcmpiA(argv[i], "/m"))
 		{
 			FunctionUnknown = TRUE;
 			WINE_FIXME("Unknown parameter /m\n");
 		}
-		else if(!strcasecmp(argv[i], "/D"))
+		else if(!lstrcmpiA(argv[i], "/D"))
 		{
 			FunctionUnknown = TRUE;
 			WINE_FIXME("Unknown parameter /D\n");