diff --git a/config-unix.mk b/config-unix.mk
index 37c4a72f..c538555e 100644
--- a/config-unix.mk
+++ b/config-unix.mk
@@ -22,7 +22,7 @@ E=
 CSTDFLAG=--std=c89 -pedantic -Wall -Wextra -Wno-unused-parameter
 CFLAGS += -g
 CPPFLAGS += -I$(SRCDIR)/src
-LDFLAGS=-lm
+LDFLAGS=-lm -pthread
 
 CPPFLAGS += -D_LARGEFILE_SOURCE
 CPPFLAGS += -D_FILE_OFFSET_BITS=64