diff --git a/js/src/old-configure.in b/js/src/old-configure.in
index 9069bc9313cb..1deca139cdc3 100644
--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -532,9 +532,6 @@ case "$target" in
             AC_MSG_ERROR(Firefox cannot be built with mingw-gcc and requires a mingw-clang toolchain to work)
         fi
 
-        CC="$CC -mwindows"
-        CXX="$CXX -mwindows"
-        CPP="$CPP -mwindows"
         DSO_LDOPTS='-shared'
         # Use temp file for windres (bug 213281)
         RCFLAGS='-O coff --use-temp-file'
diff --git a/old-configure.in b/old-configure.in
index be53c10a8b99..63be0fa9b058 100644
--- a/old-configure.in
+++ b/old-configure.in
@@ -650,9 +650,6 @@ case "$target" in
             AC_MSG_ERROR(Firefox cannot be built with mingw-gcc and requires a mingw-clang toolchain to work)
         fi
 
-        CC="$CC -mwindows"
-        CXX="$CXX -mwindows"
-        CPP="$CPP -mwindows"
         DSO_LDOPTS='-shared'
         # Use temp file for windres (bug 213281)
         RCFLAGS='-O coff --use-temp-file'