diff --git a/src/helper/Makefile.am b/src/helper/Makefile.am
index 0cfdf7c31..e8d9a6944 100644
--- a/src/helper/Makefile.am
+++ b/src/helper/Makefile.am
@@ -18,6 +18,11 @@ if IOUTIL
 libhelper_a_SOURCES += ioutil.c
 endif
 
+libhelper_a_CFLAGS =
+if IS_MINGW
+# FD_* macros are sloppy with their signs on MinGW32 platform
+libhelper_a_CFLAGS += -Wno-sign-compare
+endif
 
 noinst_HEADERS = binarybuffer.h configuration.h types.h log.h command.h \
 	time_support.h replacements.h fileio.h jim.h jim-eventloop.h \
diff --git a/src/server/Makefile.am b/src/server/Makefile.am
index 075e9560e..faf496061 100644
--- a/src/server/Makefile.am
+++ b/src/server/Makefile.am
@@ -8,6 +8,11 @@ if HTTPD
 libserver_a_SOURCES += httpd.c
 endif
 
+libserver_a_CFLAGS =
+if IS_MINGW
+# FD_* macros are sloppy with their signs on MinGW32 platform
+libserver_a_CFLAGS += -Wno-sign-compare
+endif
 
 # tcl server addons
 noinst_HEADERS += tcl_server.h