diff --git a/libs/win32/json/libjson.2008.vcproj b/libs/win32/json/libjson.2008.vcproj
index 91a371b48c..5c09e5413c 100644
--- a/libs/win32/json/libjson.2008.vcproj
+++ b/libs/win32/json/libjson.2008.vcproj
@@ -172,7 +172,7 @@
 				Optimization="2"
 				EnableIntrinsicFunctions="true"
 				AdditionalIncludeDirectories="."
-				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS"
+				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS"
 				RuntimeLibrary="2"
 				EnableFunctionLevelLinking="true"
 				UsePrecompiledHeader="0"
@@ -236,7 +236,7 @@
 				Optimization="2"
 				EnableIntrinsicFunctions="true"
 				AdditionalIncludeDirectories="."
-				PreprocessorDefinitions="WIN32;_DEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS"
+				PreprocessorDefinitions="WIN32;NDEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS"
 				RuntimeLibrary="2"
 				EnableFunctionLevelLinking="true"
 				UsePrecompiledHeader="0"
diff --git a/libs/win32/json/libjson.2010.vcxproj b/libs/win32/json/libjson.2010.vcxproj
index 5846ff3e92..a371ac2f46 100644
--- a/libs/win32/json/libjson.2010.vcxproj
+++ b/libs/win32/json/libjson.2010.vcxproj
@@ -96,7 +96,7 @@
       <Optimization>MaxSpeed</Optimization>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <AdditionalIncludeDirectories>.;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>WIN32;_DEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <WarningLevel>Level3</WarningLevel>
@@ -110,7 +110,7 @@
       <Optimization>MaxSpeed</Optimization>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <AdditionalIncludeDirectories>.;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>WIN32;_DEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_LIB;HAVE_CONFIG_H;HAVE_STDARG_H;STDC_HEADERS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <WarningLevel>Level3</WarningLevel>