diff --git a/lib/connect.c b/lib/connect.c
index 89912157e0..c4b9564a88 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -1309,7 +1309,7 @@ connect_sub_chain:
     }
 #endif /* USE_SSL */
 
-#if !defined(CURL_DISABLE_HTTP)
+#ifndef CURL_DISABLE_HTTP
     if(cf->conn->bits.tunnel_proxy) {
       result = Curl_cf_http_proxy_insert_after(cf, data);
       if(result)
@@ -1323,7 +1323,7 @@ connect_sub_chain:
 #endif /* !CURL_DISABLE_PROXY */
 
   if(ctx->state < CF_SETUP_CNNCT_HAPROXY) {
-#if !defined(CURL_DISABLE_PROXY)
+#ifndef CURL_DISABLE_PROXY
     if(data->set.haproxyprotocol) {
       if(Curl_conn_is_ssl(cf->conn, cf->sockindex)) {
         failf(data, "haproxy protocol not support with SSL "
@@ -1502,7 +1502,7 @@ CURLcode Curl_conn_setup(struct Curl_easy *data,
   Curl_resolv_unlink(data, &data->state.dns[sockindex]);
   data->state.dns[sockindex] = dns;
 
-#if !defined(CURL_DISABLE_HTTP)
+#ifndef CURL_DISABLE_HTTP
   if(!conn->cfilter[sockindex] &&
      conn->handler->protocol == CURLPROTO_HTTPS) {
     DEBUGASSERT(ssl_mode != CURL_CF_SSL_DISABLE);
diff --git a/lib/curl_ntlm_core.c b/lib/curl_ntlm_core.c
index fa3c809b97..d1ab3cb561 100644
--- a/lib/curl_ntlm_core.c
+++ b/lib/curl_ntlm_core.c
@@ -58,7 +58,7 @@
   #endif
 #elif defined(USE_WOLFSSL)
   #include <wolfssl/options.h>
-  #if !defined(NO_DES3)
+  #ifndef NO_DES3
     #define USE_OPENSSL_DES
   #endif
 #endif
@@ -129,7 +129,7 @@
 #include "curl_memory.h"
 #include "memdebug.h"
 
-#if !defined(CURL_NTLM_NOT_SUPPORTED)
+#ifndef CURL_NTLM_NOT_SUPPORTED
 /*
 * Turns a 56-bit key into being 64-bit wide.
 */
@@ -329,7 +329,7 @@ CURLcode Curl_ntlm_core_mk_lm_hash(const char *password,
                                    unsigned char *lmbuffer /* 21 bytes */)
 {
   unsigned char pw[14];
-#if !defined(CURL_NTLM_NOT_SUPPORTED)
+#ifndef CURL_NTLM_NOT_SUPPORTED
   static const unsigned char magic[] = {
     0x4B, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25 /* i.e. KGS!@#$% */
   };
@@ -380,7 +380,7 @@ static void ascii_to_unicode_le(unsigned char *dest, const char *src,
   }
 }
 
-#if !defined(USE_WINDOWS_SSPI)
+#ifndef USE_WINDOWS_SSPI
 
 static void ascii_uppercase_to_unicode_le(unsigned char *dest,
                                           const char *src, size_t srclen)
@@ -422,7 +422,7 @@ CURLcode Curl_ntlm_core_mk_nt_hash(const char *password,
   return result;
 }
 
-#if !defined(USE_WINDOWS_SSPI)
+#ifndef USE_WINDOWS_SSPI
 
 #define NTLMv2_BLOB_SIGNATURE "\x01\x01\x00\x00"
 #define NTLMv2_BLOB_LEN       (44 -16 + ntlm->target_info_len + 4)
diff --git a/lib/curl_ntlm_core.h b/lib/curl_ntlm_core.h
index 31cf95ccef..584f4a17d5 100644
--- a/lib/curl_ntlm_core.h
+++ b/lib/curl_ntlm_core.h
@@ -47,7 +47,7 @@ CURLcode Curl_ntlm_core_mk_lm_hash(const char *password,
 CURLcode Curl_ntlm_core_mk_nt_hash(const char *password,
                                    unsigned char *ntbuffer /* 21 bytes */);
 
-#if !defined(USE_WINDOWS_SSPI)
+#ifndef USE_WINDOWS_SSPI
 
 CURLcode Curl_hmac_md5(const unsigned char *key, unsigned int keylen,
                        const unsigned char *data, unsigned int datalen,
diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index bdb87f4d49..f5e16d7633 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -1003,7 +1003,7 @@ int getpwuid_r(uid_t uid, struct passwd *pwd, char *buf,
 #endif
 
 #if defined(USE_UNIX_SOCKETS) && defined(_WIN32)
-#  if !defined(UNIX_PATH_MAX)
+#  ifndef UNIX_PATH_MAX
      /* Replicating logic present in afunix.h
         (distributed with newer Windows 10 SDK versions only) */
 #    define UNIX_PATH_MAX 108
diff --git a/lib/ldap.c b/lib/ldap.c
index 6c5fb433b0..7fc0da0b2d 100644
--- a/lib/ldap.c
+++ b/lib/ldap.c
@@ -248,7 +248,7 @@ static int ldap_win_bind_auth(LDAP *server, const char *user,
   }
   else
 #endif
-#if !defined(CURL_DISABLE_DIGEST_AUTH)
+#ifndef CURL_DISABLE_DIGEST_AUTH
   if(authflags & CURLAUTH_DIGEST) {
     method = LDAP_AUTH_DIGEST;
   }
diff --git a/lib/md5.c b/lib/md5.c
index 591ce32ed0..fea20377fe 100644
--- a/lib/md5.c
+++ b/lib/md5.c
@@ -177,7 +177,7 @@ static void my_md5_update(void *ctx,
                           const unsigned char *data,
                           unsigned int length)
 {
-#if !defined(HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS)
+#ifndef HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS
   (void)mbedtls_md5_update(ctx, data, length);
 #else
   (void)mbedtls_md5_update_ret(ctx, data, length);
@@ -186,7 +186,7 @@ static void my_md5_update(void *ctx,
 
 static void my_md5_final(unsigned char *digest, void *ctx)
 {
-#if !defined(HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS)
+#ifndef HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS
   (void)mbedtls_md5_finish(ctx, digest);
 #else
   (void)mbedtls_md5_finish_ret(ctx, digest);
diff --git a/lib/multihandle.h b/lib/multihandle.h
index 4bf2dd811c..dbad164bc5 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -80,7 +80,7 @@ typedef enum {
 
 #define CURLPIPE_ANY (CURLPIPE_MULTIPLEX)
 
-#if !defined(CURL_DISABLE_SOCKETPAIR)
+#ifndef CURL_DISABLE_SOCKETPAIR
 #define ENABLE_WAKEUP
 #endif
 
diff --git a/lib/rand.c b/lib/rand.c
index 8529f9ede1..d6f4a2dffc 100644
--- a/lib/rand.c
+++ b/lib/rand.c
@@ -100,7 +100,7 @@ CURLcode Curl_win32_random(unsigned char *entropy, size_t length)
 }
 #endif
 
-#if !defined(USE_SSL)
+#ifndef USE_SSL
 /* ---- possibly non-cryptographic version following ---- */
 static CURLcode weak_random(struct Curl_easy *data,
                             unsigned char *entropy,
diff --git a/lib/setopt.c b/lib/setopt.c
index 1be45dc05b..3d1ce791e8 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -646,7 +646,7 @@ static CURLcode setopt_long(struct Curl_easy *data, CURLoption option,
     data->set.postfieldsize = arg;
     break;
 #ifndef CURL_DISABLE_HTTP
-#if !defined(CURL_DISABLE_COOKIES)
+#ifndef CURL_DISABLE_COOKIES
   case CURLOPT_COOKIESESSION:
     /*
      * Set this option to TRUE to start a new "cookie session". It will
@@ -1778,7 +1778,7 @@ static CURLcode setopt_cptr(struct Curl_easy *data, CURLoption option,
     }
     return Curl_setstropt(&data->set.str[STRING_ENCODING], ptr);
 
-#if !defined(CURL_DISABLE_AWS)
+#ifndef CURL_DISABLE_AWS
   case CURLOPT_AWS_SIGV4:
     /*
      * String that is merged to some authentication
@@ -1810,7 +1810,7 @@ static CURLcode setopt_cptr(struct Curl_easy *data, CURLoption option,
      */
     return Curl_setstropt(&data->set.str[STRING_USERAGENT], ptr);
 
-#if !defined(CURL_DISABLE_COOKIES)
+#ifndef CURL_DISABLE_COOKIES
   case CURLOPT_COOKIE:
     /*
      * Cookie string to send to the remote server in the request.
diff --git a/lib/sha256.c b/lib/sha256.c
index e78ad1f5d3..4d71c9b4ad 100644
--- a/lib/sha256.c
+++ b/lib/sha256.c
@@ -134,7 +134,7 @@ typedef mbedtls_sha256_context my_sha256_ctx;
 
 static CURLcode my_sha256_init(void *ctx)
 {
-#if !defined(HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS)
+#ifndef HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS
   (void)mbedtls_sha256_starts(ctx, 0);
 #else
   (void)mbedtls_sha256_starts_ret(ctx, 0);
@@ -146,7 +146,7 @@ static void my_sha256_update(void *ctx,
                              const unsigned char *data,
                              unsigned int length)
 {
-#if !defined(HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS)
+#ifndef HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS
   (void)mbedtls_sha256_update(ctx, data, length);
 #else
   (void)mbedtls_sha256_update_ret(ctx, data, length);
@@ -155,7 +155,7 @@ static void my_sha256_update(void *ctx,
 
 static void my_sha256_final(unsigned char *digest, void *ctx)
 {
-#if !defined(HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS)
+#ifndef HAS_MBEDTLS_RESULT_CODE_BASED_FUNCTIONS
   (void)mbedtls_sha256_finish(ctx, digest);
 #else
   (void)mbedtls_sha256_finish_ret(ctx, digest);
@@ -191,7 +191,7 @@ struct sha256_ctx {
 };
 typedef struct sha256_ctx my_sha256_ctx;
 
-#if !defined(CALG_SHA_256)
+#ifndef CALG_SHA_256
 #define CALG_SHA_256 0x0000800c
 #endif