diff --git a/crypto/comp/c_zlib.c b/crypto/comp/c_zlib.c
index c3167fcea..7553a2d10 100644
--- a/crypto/comp/c_zlib.c
+++ b/crypto/comp/c_zlib.c
@@ -178,9 +178,12 @@ static int zlib_stateful_init(COMP_CTX *ctx)
 	CRYPTO_new_ex_data(CRYPTO_EX_INDEX_COMP,ctx,&ctx->ex_data);
 	if (zlib_stateful_ex_idx == -1)
 		{
-		zlib_stateful_ex_idx =
-			CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_COMP,
-				0,NULL,NULL,NULL,zlib_stateful_free_ex_data);
+		CRYPTO_w_lock(CRYPTO_LOCK_COMP);
+		if (zlib_stateful_ex_idx == -1)
+			zlib_stateful_ex_idx =
+				CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_COMP,
+					0,NULL,NULL,NULL,zlib_stateful_free_ex_data);
+		CRYPTO_w_unlock(CRYPTO_LOCK_COMP);
 		if (zlib_stateful_ex_idx == -1)
 			goto err;
 		}
diff --git a/crypto/cryptlib.c b/crypto/cryptlib.c
index 9c38f15ab..009c3be4c 100644
--- a/crypto/cryptlib.c
+++ b/crypto/cryptlib.c
@@ -168,7 +168,8 @@ static const char* lock_names[CRYPTO_NUM_LOCKS] =
 	"bn",
 	"ec_pre_comp",
 	"store",
-#if CRYPTO_NUM_LOCKS != 38
+	"comp",
+#if CRYPTO_NUM_LOCKS != 39
 # error "Inconsistency between crypto.h and cryptlib.c"
 #endif
 	};
diff --git a/crypto/crypto.h b/crypto/crypto.h
index dd90cfa55..5238e5306 100644
--- a/crypto/crypto.h
+++ b/crypto/crypto.h
@@ -203,7 +203,8 @@ typedef struct openssl_item_st
 #define CRYPTO_LOCK_BN  		35
 #define CRYPTO_LOCK_EC_PRE_COMP		36
 #define CRYPTO_LOCK_STORE		37
-#define CRYPTO_NUM_LOCKS		38
+#define CRYPTO_LOCK_COMP		38
+#define CRYPTO_NUM_LOCKS		39
 
 #define CRYPTO_LOCK		1
 #define CRYPTO_UNLOCK		2