diff --git a/Make.inc b/Make.inc
index c0ad81bfa0c2f..f8507b3d6c019 100644
--- a/Make.inc
+++ b/Make.inc
@@ -869,7 +869,7 @@ UNTRUSTED_SYSTEM_LIBM := 1
 endif
 
 # Threads
-ifeq ($(JULIA_THREADS), 1)
+ifneq ($(JULIA_THREADS), 0)
 JCPPFLAGS += -DJULIA_ENABLE_THREADING
 endif
 
diff --git a/src/options.h b/src/options.h
index 948f00e857fed..74a852b99ae31 100644
--- a/src/options.h
+++ b/src/options.h
@@ -97,7 +97,7 @@
 
 // defaults for # threads
 #define NUM_THREADS_NAME                "JULIA_NUM_THREADS"
-#define DEFAULT_NUM_THREADS             4
+#define DEFAULT_NUM_THREADS             1
 
 // affinitization behavior
 #define MACHINE_EXCLUSIVE_NAME          "JULIA_EXCLUSIVE"