diff --git a/src/gc/configure b/src/gc/configure
index 002d616a5..f76542799 100755
--- a/src/gc/configure
+++ b/src/gc/configure
@@ -4912,7 +4912,7 @@ echo "$as_me: error: \"Pthreads not supported by the GC on this platform.\"" >&2
     cat >>confdefs.h <<\_ACEOF
 #define GC_WIN32_THREADS 1
 _ACEOF
-    win32_threads=1
+    win32_threads=true
         cat >>confdefs.h <<\_ACEOF
 #define NO_GETENV 1
 _ACEOF