diff --git a/dll/win32/shell32/shlfileop.cpp b/dll/win32/shell32/shlfileop.cpp
index f90f3265773..475aee0421a 100644
--- a/dll/win32/shell32/shlfileop.cpp
+++ b/dll/win32/shell32/shlfileop.cpp
@@ -29,7 +29,11 @@ WINE_DEFAULT_DEBUG_CHANNEL(shell);
 #define IsAttrib(x, y)  ((INVALID_FILE_ATTRIBUTES != (x)) && ((x) & (y)))
 #define IsAttribFile(x) (!((x) & FILE_ATTRIBUTE_DIRECTORY))
 #define IsAttribDir(x)  IsAttrib(x, FILE_ATTRIBUTE_DIRECTORY)
-#define IsDotDir(x)     ((x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#ifdef __REACTOS__
+    #define IsDotDir(x)     ((x) && (x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#else
+    #define IsDotDir(x)     ((x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#endif
 
 #define FO_MASK         0xF
 
diff --git a/modules/rostests/winetests/kernel32/file.c b/modules/rostests/winetests/kernel32/file.c
index ee91e62e419..79b7918ba71 100644
--- a/modules/rostests/winetests/kernel32/file.c
+++ b/modules/rostests/winetests/kernel32/file.c
@@ -1850,7 +1850,11 @@ static void test_DeleteFileW( void )
     ok(ret == TRUE, "expected to remove directory deletefile\n");
 }
 
-#define IsDotDir(x)     ((x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#ifdef __REACTOS__
+    #define IsDotDir(x)     ((x) && (x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#else
+    #define IsDotDir(x)     ((x[0] == '.') && ((x[1] == 0) || ((x[1] == '.') && (x[2] == 0))))
+#endif
 
 static void test_MoveFileA(void)
 {