diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e9a9e392..7798d0bfc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,7 +125,7 @@ if(MSVC)
 endif(MSVC)
 
 if(PNG_SHARED OR  NOT MSVC)
-	#if building msvc static this has NOT do be defined
+	#if building msvc static this has NOT to be defined
 	add_definitions(-DZLIB_DLL)
 endif()