diff --git a/ntlm.c b/ntlm.c
index 21c8b62..60699ee 100644
--- a/ntlm.c
+++ b/ntlm.c
@@ -28,14 +28,25 @@
 #include "proxytunnel.h"
 #include <ctype.h>
 #include <sys/time.h>
-#include <openssl/md4.h>
-#include <openssl/md5.h>
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	#include <openssl/provider.h>
+	#include <openssl/evp.h>
+#else
+	#include <openssl/md4.h>
+	#include <openssl/md5.h>
+#endif
 
 #define TYPE1_DATA_SEG 8
 #define TYPE2_BUF_SIZE 2048
 #define DOMAIN_BUFLEN 256
 #define LM2_DIGEST_LEN 24
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+const EVP_MD *md4alg;
+const EVP_MD *md5alg;
+EVP_MD_CTX *mdctx;
+#endif
+
 int ntlm_challenge = 0;
 void message( char *s, ... );
 int unicode = 0;
@@ -58,6 +69,16 @@ uint32_t flags;
 
 unsigned char lm2digest[LM2_DIGEST_LEN];
 
+void init_ntlm() {
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	OSSL_PROVIDER_load(NULL, "default");
+	OSSL_PROVIDER_load(NULL, "legacy");
+	md4alg = EVP_md4();
+	md5alg = EVP_md5();
+	mdctx = EVP_MD_CTX_new();
+#endif
+}
+
 void build_type1() {
 	ntlm_type1 *type1;
 	int len = sizeof(ntlm_type1) + sizeof(unsigned char) * TYPE1_DATA_SEG;
@@ -237,7 +258,10 @@ unsigned char* key; /* pointer to authentication key */
 int key_len; /* length of authentication key */
 unsigned char digest[16]; /* caller digest to be filled in */
 {
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+#else
 	MD5_CTX context;
+#endif
 	unsigned char k_ipad[65];    /* inner padding - key XORd with ipad */
 	unsigned char k_opad[65];    /* outer padding - key XORd with opad */
 	unsigned char tk[16];
@@ -245,10 +269,15 @@ unsigned char digest[16]; /* caller digest to be filled in */
 
 	/* if key is longer than 64 bytes reset it to key=MD5(key) */
 	if (key_len > 64) {
-		MD5_CTX tctx;
-		MD5_Init( &tctx );
-		MD5_Update( &tctx, key, key_len );
-		MD5_Final( tk, &tctx );
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+		EVP_DigestInit_ex(mdctx, md5alg, NULL);
+		EVP_DigestUpdate(mdctx, key, key_len);
+		EVP_DigestFinal_ex(mdctx, tk, NULL);
+#else
+		MD5_Init(&context);
+		MD5_Update(&context, key, key_len);
+		MD5_Final(tk, &context);
+#endif
 		key = tk;
 		key_len = 16;
 	}
@@ -277,22 +306,39 @@ unsigned char digest[16]; /* caller digest to be filled in */
 	}
 
 	/* perform inner MD5 */
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	EVP_DigestInit_ex(mdctx, md5alg, NULL);  /* init context for 1st pass */
+	EVP_DigestUpdate(mdctx, k_ipad, 64);     /* start with inner pad */
+	EVP_DigestUpdate(mdctx, text, text_len); /* then text of datagram */
+	EVP_DigestFinal_ex(mdctx, digest, NULL); /* finish up 1st pass */
+#else
 	MD5_Init(&context);                   /* init context for 1st pass */
 	MD5_Update(&context, k_ipad, 64);     /* start with inner pad */
 	MD5_Update(&context, text, text_len); /* then text of datagram */
 	MD5_Final(digest, &context);          /* finish up 1st pass */
+#endif
 
 	/* perform outer MD5 */
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	EVP_DigestInit_ex(mdctx, md5alg, NULL);  /* init context for 1st pass */
+	EVP_DigestUpdate(mdctx, k_opad, 64);     /* start with inner pad */
+	EVP_DigestUpdate(mdctx, digest, 16);     /* then text of datagram */
+	EVP_DigestFinal_ex(mdctx, digest, NULL); /* finish up 1st pass */
+#else
 	MD5_Init(&context);                   /* init context for 2nd pass */
 	MD5_Update(&context, k_opad, 64);     /* start with outer pad */
 	MD5_Update(&context, digest, 16);     /* then results of 1st hash */
 	MD5_Final(digest, &context);          /* finish up 2nd pass */
+#endif
 }
 
 void build_ntlm2_response() {
 	int i, j;
 	int passlen = 0;
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+#else
 	MD4_CTX passcontext;
+#endif
 	unsigned char passdigest[16];
 	unsigned char *userdom;
 	int userdomlen;
@@ -317,9 +363,15 @@ void build_ntlm2_response() {
 		}
 	}
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	EVP_DigestInit_ex(mdctx, md4alg, NULL);
+	EVP_DigestUpdate(mdctx, unipasswd, passlen);
+	EVP_DigestFinal_ex(mdctx, passdigest, NULL);
+#else
 	MD4_Init (&passcontext);
 	MD4_Update (&passcontext, unipasswd, passlen);
 	MD4_Final (passdigest, &passcontext);
+#endif
 
 	if( args_info.verbose_flag ) {
 		message("NTLM: MD4 of password is: ");
diff --git a/ntlm.h b/ntlm.h
index 3d91c8d..48a3384 100644
--- a/ntlm.h
+++ b/ntlm.h
@@ -21,6 +21,7 @@
 
 #include <stdint.h>
 
+void init_ntlm();
 void build_type1();
 int parse_type2(unsigned char *buf);
 void build_type3_response();
diff --git a/proxytunnel.c b/proxytunnel.c
index e489a5a..a847223 100644
--- a/proxytunnel.c
+++ b/proxytunnel.c
@@ -420,6 +420,11 @@ int main( int argc, char *argv[] ) {
 
 	signal( SIGHUP, signal_handler );
 
+	/* Initialize the NTLM module, if needed. */
+	if (args_info.ntlm_flag) {
+		init_ntlm();
+	}
+
 	/* If the usename is given, but password is not, prompt for it */
 	if( args_info.user_given && !args_info.pass_given ) {
 		char *cp;