diff --git a/CMakeLists.txt b/CMakeLists.txt
index afab40cf..d5e61f4a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -269,7 +269,7 @@ if(MSVC)
     -DWIN32
     -DDLL_EXPORT
     # NB: May require tweaking for highly connected applications.
-    -DFD_SETSIZE=1025
+    -DFD_SETSIZE=1024
     -D_CRT_SECURE_NO_WARNINGS)
 
   # Parallel make.
diff --git a/builds/mingw32/Makefile.mingw32 b/builds/mingw32/Makefile.mingw32
index 95cea7d3..447cf504 100644
--- a/builds/mingw32/Makefile.mingw32
+++ b/builds/mingw32/Makefile.mingw32
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-Wall -Os -g -DDLL_EXPORT -DFD_SETSIZE=1025 -I.
+CFLAGS=-Wall -Os -g -DDLL_EXPORT -DFD_SETSIZE=1024 -I.
 LIBS=-lws2_32
 
 OBJS = ctx.o reaper.o dist.o err.o \
diff --git a/builds/msvc/libzmq/libzmq.vcproj b/builds/msvc/libzmq/libzmq.vcproj
index 01adfd1a..9cdef064 100644
--- a/builds/msvc/libzmq/libzmq.vcproj
+++ b/builds/msvc/libzmq/libzmq.vcproj
@@ -40,7 +40,7 @@
 			/>
 			<Tool
 				Name="VCCLCompilerTool"
-				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1025 -D_CRT_SECURE_NO_WARNINGS"
+				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1024 -D_CRT_SECURE_NO_WARNINGS"
 				Optimization="0"
 				PreprocessorDefinitions="NOMINMAX"
 				MinimalRebuild="true"
@@ -114,7 +114,7 @@
 			/>
 			<Tool
 				Name="VCCLCompilerTool"
-				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1025 -D_CRT_SECURE_NO_WARNINGS"
+				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1024 -D_CRT_SECURE_NO_WARNINGS"
 				Optimization="2"
 				EnableIntrinsicFunctions="true"
 				RuntimeLibrary="2"
@@ -188,7 +188,7 @@
 			/>
 			<Tool
 				Name="VCCLCompilerTool"
-				AdditionalOptions="-DZMQ_STATIC -DFD_SETSIZE=1025 -D_CRT_SECURE_NO_WARNINGS"
+				AdditionalOptions="-DZMQ_STATIC -DFD_SETSIZE=1024 -D_CRT_SECURE_NO_WARNINGS"
 				Optimization="0"
 				PreprocessorDefinitions="NOMINMAX"
 				MinimalRebuild="true"
@@ -254,7 +254,7 @@
 			/>
 			<Tool
 				Name="VCCLCompilerTool"
-				AdditionalOptions="-DZMQ_STATIC -DFD_SETSIZE=1025 -D_CRT_SECURE_NO_WARNINGS"
+				AdditionalOptions="-DZMQ_STATIC -DFD_SETSIZE=1024 -D_CRT_SECURE_NO_WARNINGS"
 				Optimization="2"
 				EnableIntrinsicFunctions="true"
 				RuntimeLibrary="2"
@@ -319,7 +319,7 @@
 			/>
 			<Tool
 				Name="VCCLCompilerTool"
-				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1025 -D_CRT_SECURE_NO_WARNINGS"
+				AdditionalOptions="-DDLL_EXPORT -DFD_SETSIZE=1024 -D_CRT_SECURE_NO_WARNINGS"
 				Optimization="2"
 				EnableIntrinsicFunctions="true"
 				AdditionalIncludeDirectories="../../../../OpenPGM/include"
diff --git a/builds/msvc/properties/ZeroMQ.props b/builds/msvc/properties/ZeroMQ.props
index 2bc89e0c..c326486b 100644
--- a/builds/msvc/properties/ZeroMQ.props
+++ b/builds/msvc/properties/ZeroMQ.props
@@ -13,7 +13,7 @@
       <Command>copy ..\platform.hpp ..\..\..\src</Command>
     </PreBuildEvent>
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;DLL_EXPORT;FD_SETSIZE=1025;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;DLL_EXPORT;FD_SETSIZE=1024;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>Ws2_32.lib;Rpcrt4.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/builds/msvc/properties/ZeroMQ_Static.props b/builds/msvc/properties/ZeroMQ_Static.props
index 9cdb107a..dec17f85 100644
--- a/builds/msvc/properties/ZeroMQ_Static.props
+++ b/builds/msvc/properties/ZeroMQ_Static.props
@@ -13,7 +13,7 @@
       <Command>copy ..\platform.hpp ..\..\..\src</Command>
     </PreBuildEvent>
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;ZMQ_STATIC;FD_SETSIZE=1025;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;ZMQ_STATIC;FD_SETSIZE=1024;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Lib>
       <AdditionalDependencies>Ws2_32.lib;Rpcrt4.lib;%(AdditionalDependencies)</AdditionalDependencies>