diff --git a/crypto777/m_js b/crypto777/m_js
index dac261162..e0aa6c132 100755
--- a/crypto777/m_js
+++ b/crypto777/m_js
@@ -1,4 +1,4 @@
 git pull
 rm *.o
-emcc -c -s ALLOW_MEMORY_GROWTH=1  -O2 *.c jpeg/*.c jpeg/unix/*.c 
+emcc -c -s USE_PTHREADS=1 -s ALLOW_MEMORY_GROWTH=1  -O2 *.c jpeg/*.c jpeg/unix/*.c 
 rm -f ../agents/libcrypto777.a; emar rcu ../agents/libcrypto777.a *.o 
diff --git a/iguana/m_js b/iguana/m_js
index dae6c86f2..f64f820c5 100755
--- a/iguana/m_js
+++ b/iguana/m_js
@@ -1,6 +1,6 @@
 rm ../agents/iguana *.o
 git pull
 cd secp256k1; ./m_js; cd ..
-emcc -s ALLOW_MEMORY_GROWTH=1 -Wno-deprecated -c -O2 *.c databases/iguana_DB.c
+emcc -s USE_PTHREADS=1 -s ALLOW_MEMORY_GROWTH=1 -Wno-deprecated -c -O2 *.c databases/iguana_DB.c
 #emcc -s USE_PTHREADS=1 -Wno-deprecated -c  main.c iguana777.c iguana_bundles.c
-emcc -s ALLOW_MEMORY_GROWTH=1 -o iguana.html -O2 *.o ../agents/libcrypto777.a -lm
+emcc -s USE_PTHREADS=1 -s ALLOW_MEMORY_GROWTH=1 -o iguana.html -O2 *.o ../agents/libcrypto777.a -lm
diff --git a/iguana/secp256k1/m_js b/iguana/secp256k1/m_js
index ad516055e..ccf5301bc 100755
--- a/iguana/secp256k1/m_js
+++ b/iguana/secp256k1/m_js
@@ -1 +1 @@
-emcc -c -o ../secp256k1.o -s ALLOW_MEMORY_GROWTH=1 -I. -I./src  -I./include -I./src -O3 -W -std=c89 -pedantic -Wall -Wextra -Wcast-align -Wnested-externs -Wshadow -Wstrict-prototypes -Wno-unused-function -Wno-long-long -Wno-overlength-strings -fvisibility=hidden -DHAVE_CONFIG_H src/secp256k1.c
+emcc -c -o ../secp256k1.o -s USE_PTHREADS=1 -s ALLOW_MEMORY_GROWTH=1 -I. -I./src  -I./include -I./src -O3 -W -std=c89 -pedantic -Wall -Wextra -Wcast-align -Wnested-externs -Wshadow -Wstrict-prototypes -Wno-unused-function -Wno-long-long -Wno-overlength-strings -fvisibility=hidden -DHAVE_CONFIG_H src/secp256k1.c