diff --git a/lib/crypto_backend/cipher_generic.c b/lib/crypto_backend/cipher_generic.c
index 746cfcf2b..00aa43f5f 100644
--- a/lib/crypto_backend/cipher_generic.c
+++ b/lib/crypto_backend/cipher_generic.c
@@ -19,9 +19,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <string.h>
-#include <stdbool.h>
 #include <errno.h>
+#include <strings.h>
 #include "crypto_backend.h"
 
 struct cipher_alg {
diff --git a/lib/crypto_backend/crc32.c b/lib/crypto_backend/crc32.c
index 7a12a8e7d..c0025ed49 100644
--- a/lib/crypto_backend/crc32.c
+++ b/lib/crypto_backend/crc32.c
@@ -38,8 +38,6 @@
  *
  */
 
-#include <stdio.h>
-
 #include "crypto_backend.h"
 
 static const uint32_t crc32_tab[] = {
diff --git a/lib/crypto_backend/crypto_cipher_kernel.c b/lib/crypto_backend/crypto_cipher_kernel.c
index 50b003174..fcd838a2d 100644
--- a/lib/crypto_backend/crypto_cipher_kernel.c
+++ b/lib/crypto_backend/crypto_cipher_kernel.c
@@ -19,10 +19,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include <stdbool.h>
 #include <errno.h>
 #include <unistd.h>
 #include <sys/socket.h>
diff --git a/lib/crypto_backend/crypto_gcrypt.c b/lib/crypto_backend/crypto_gcrypt.c
index 5b12088ef..d10ca7cbf 100644
--- a/lib/crypto_backend/crypto_gcrypt.c
+++ b/lib/crypto_backend/crypto_gcrypt.c
@@ -19,9 +19,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <string.h>
 #include <stdio.h>
 #include <errno.h>
+#include <strings.h>
 #include <gcrypt.h>
 #include <pthread.h>
 #include "crypto_backend_internal.h"
diff --git a/lib/crypto_backend/crypto_kernel.c b/lib/crypto_backend/crypto_kernel.c
index be6051a91..cc23ceb2d 100644
--- a/lib/crypto_backend/crypto_kernel.c
+++ b/lib/crypto_backend/crypto_kernel.c
@@ -19,7 +19,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>
diff --git a/lib/crypto_backend/crypto_nettle.c b/lib/crypto_backend/crypto_nettle.c
index 837fed8d9..d288e6985 100644
--- a/lib/crypto_backend/crypto_nettle.c
+++ b/lib/crypto_backend/crypto_nettle.c
@@ -20,7 +20,6 @@
  */
 
 #include <stdlib.h>
-#include <string.h>
 #include <errno.h>
 #include <nettle/sha.h>
 #include <nettle/sha3.h>
diff --git a/lib/crypto_backend/crypto_nss.c b/lib/crypto_backend/crypto_nss.c
index e394d16c2..cfb554f31 100644
--- a/lib/crypto_backend/crypto_nss.c
+++ b/lib/crypto_backend/crypto_nss.c
@@ -19,7 +19,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <string.h>
+#include <stdio.h>
 #include <errno.h>
 #include <nss.h>
 #include <pk11pub.h>
diff --git a/lib/crypto_backend/crypto_openssl.c b/lib/crypto_backend/crypto_openssl.c
index 8276d561e..4cf5a4c92 100644
--- a/lib/crypto_backend/crypto_openssl.c
+++ b/lib/crypto_backend/crypto_openssl.c
@@ -28,9 +28,10 @@
  * for all of the code used other than OpenSSL.
  */
 
-#include <string.h>
+#include <stdio.h>
 #include <errno.h>
 #include <limits.h>
+#include <strings.h>
 #include <openssl/crypto.h>
 #include <openssl/evp.h>
 #include <openssl/hmac.h>