diff --git a/src/crypto/fipsmodule/rand/internal.h b/src/crypto/fipsmodule/rand/internal.h
index 127e5d1..87fc6f0 100644
--- a/src/crypto/fipsmodule/rand/internal.h
+++ b/src/crypto/fipsmodule/rand/internal.h
@@ -27,7 +27,7 @@ extern "C" {
 
 
 #if !defined(OPENSSL_WINDOWS) && !defined(OPENSSL_FUCHSIA) && \
-    !defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE) && !defined(OPENSSL_TRUSTY)
+  !defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE) && !defined(OPENSSL_TRUSTY) && !defined(__EMSCRIPTEN__)
 #define OPENSSL_URANDOM
 #endif
 
diff --git a/src/crypto/internal.h b/src/crypto/internal.h
index b288583..b2e9321 100644
--- a/src/crypto/internal.h
+++ b/src/crypto/internal.h
@@ -130,6 +130,10 @@
 #endif
 #endif
 
+#if defined(__EMSCRIPTEN__)
+#undef OPENSSL_THREADS
+#endif
+
 #if defined(OPENSSL_THREADS) && \
     (!defined(OPENSSL_WINDOWS) || defined(__MINGW32__))
 #include <pthread.h>
@@ -493,7 +497,7 @@ OPENSSL_EXPORT void CRYPTO_once(CRYPTO_once_t *once, void (*init)(void));
 
 // Automatically enable C11 atomics if implemented.
 #if !defined(OPENSSL_C11_ATOMIC) && !defined(__STDC_NO_ATOMICS__) && \
-    defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+    defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && !defined(__EMSCRIPTEN__)
 #define OPENSSL_C11_ATOMIC
 #endif
 
diff --git a/src/crypto/rand_extra/deterministic.c b/src/crypto/rand_extra/deterministic.c
index 435f063..13a77db 100644
--- a/src/crypto/rand_extra/deterministic.c
+++ b/src/crypto/rand_extra/deterministic.c
@@ -14,7 +14,7 @@
 
 #include <openssl/rand.h>
 
-#if defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE)
+#if defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE) || defined(__EMSCRIPTEN__)
 
 #include <string.h>