diff --git a/library/pem.c b/library/pem.c
index cd9dd2ab16..5e8f26858d 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -46,14 +46,19 @@
 
 #include "legacy_or_psa.h"
 
+#if defined(MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
+    ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
+#define PEM_RFC1421
+#endif /* MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA && MBEDTLS_CIPHER_MODE_CBC &&
+          ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
+
 #if defined(MBEDTLS_PEM_PARSE_C)
 void mbedtls_pem_init( mbedtls_pem_context *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_pem_context ) );
 }
 
-#if defined(MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
-    ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
+#if defined(PEM_RFC1421 )
 /*
  * Read a 16-byte hex string and convert it to binary
  */
@@ -340,8 +345,7 @@ exit:
 }
 #endif /* MBEDTLS_AES_C */
 
-#endif /* MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA && MBEDTLS_CIPHER_MODE_CBC &&
-          ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
+#endif /* PEM_RFC1421  */
 
 int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const char *footer,
                      const unsigned char *data, const unsigned char *pwd,
@@ -351,15 +355,13 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
     size_t len;
     unsigned char *buf;
     const unsigned char *s1, *s2, *end;
-#if defined(MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
-    ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
+#if defined(PEM_RFC1421 )
     unsigned char pem_iv[16];
     mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
 #else
     ((void) pwd);
     ((void) pwdlen);
-#endif /* MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA && MBEDTLS_CIPHER_MODE_CBC &&
-          ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
+#endif /* PEM_RFC1421  */
 
     if( ctx == NULL )
         return( MBEDTLS_ERR_PEM_BAD_INPUT_DATA );
@@ -391,8 +393,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
     if( s2 - s1 >= 22 && memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
     {
-#if defined(MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
-    ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
+#if defined(PEM_RFC1421 )
         enc++;
 
         s1 += 22;
@@ -454,8 +455,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
         else return( MBEDTLS_ERR_PEM_INVALID_DATA );
 #else
         return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
-#endif /* MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA && MBEDTLS_CIPHER_MODE_CBC &&
-          ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
+#endif /* PEM_RFC1421  */
     }
 
     if( s1 >= s2 )
@@ -478,8 +478,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
     if( enc != 0 )
     {
-#if defined(MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA) && defined(MBEDTLS_CIPHER_MODE_CBC) &&         \
-    ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
+#if defined(PEM_RFC1421 )
         if( pwd == NULL )
         {
             mbedtls_platform_zeroize( buf, len );
@@ -527,8 +526,7 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
         mbedtls_platform_zeroize( buf, len );
         mbedtls_free( buf );
         return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
-#endif /* MBEDTLS_HAS_ALG_MD5_VIA_MD_OR_PSA_BASED_ON_USE_PSA && MBEDTLS_CIPHER_MODE_CBC &&
-          ( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
+#endif /* PEM_RFC1421  */
     }
 
     ctx->buf = buf;