diff --git a/SoObjects/SOGo/NSData+Crypto.m b/SoObjects/SOGo/NSData+Crypto.m
index c1d1558ba..eed4b04e8 100644
--- a/SoObjects/SOGo/NSData+Crypto.m
+++ b/SoObjects/SOGo/NSData+Crypto.m
@@ -43,6 +43,10 @@
 #define SHA256_DIGEST_LENGTH 32
 #define SHA512_DIGEST_LENGTH 64
 #elif defined(HAVE_OPENSSL)
+#include <openssl/evp.h>
+#include <openssl/md4.h>
+#include <openssl/md5.h>
+#include <openssl/sha.h>
 #else
 #error this module requires either gnutls or openssl
 #endif
diff --git a/UI/MailPartViewers/UIxMailPartSignedViewer.m b/UI/MailPartViewers/UIxMailPartSignedViewer.m
index 3db088396..091777b90 100644
--- a/UI/MailPartViewers/UIxMailPartSignedViewer.m
+++ b/UI/MailPartViewers/UIxMailPartSignedViewer.m
@@ -19,10 +19,16 @@
  */
 
 #ifdef HAVE_OPENSSL
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <openssl/pkcs7.h>
+#include <openssl/x509.h>
 #endif
 
+#import <Foundation/NSData.h>
 #import <Foundation/NSDictionary.h>
 #import <Foundation/NSValue.h>
+#import <Mailer/SOGoMailObject.h>
 
 #import "UIxMailRenderingContext.h"
 #import "UIxMailPartSignedViewer.h"