diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index a5acf5b8b..472c28aa8 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -85,7 +85,8 @@ int main( void )
 
 int main( int argc, char *argv[] )
 {
-    int ret = 1, i, n;
+    int ret = 1, i;
+    unsigned n;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     int mode;
     size_t keylen, ilen, olen;
diff --git a/programs/pkey/pk_decrypt.c b/programs/pkey/pk_decrypt.c
index bf425079e..998c7ac89 100644
--- a/programs/pkey/pk_decrypt.c
+++ b/programs/pkey/pk_decrypt.c
@@ -64,7 +64,8 @@ int main( void )
 int main( int argc, char *argv[] )
 {
     FILE *f;
-    int ret = 1, c;
+    int ret = 1;
+    unsigned c;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     size_t i, olen = 0;
     mbedtls_pk_context pk;
diff --git a/programs/pkey/rsa_decrypt.c b/programs/pkey/rsa_decrypt.c
index ff71bd055..c725f7ca1 100644
--- a/programs/pkey/rsa_decrypt.c
+++ b/programs/pkey/rsa_decrypt.c
@@ -65,7 +65,7 @@ int main( int argc, char *argv[] )
     FILE *f;
     int ret = 1;
     int exit_code = MBEDTLS_EXIT_FAILURE;
-    int c;
+    unsigned c;
     size_t i;
     mbedtls_rsa_context rsa;
     mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
diff --git a/programs/pkey/rsa_verify.c b/programs/pkey/rsa_verify.c
index 94f0ef9ce..74030e45e 100644
--- a/programs/pkey/rsa_verify.c
+++ b/programs/pkey/rsa_verify.c
@@ -59,7 +59,8 @@ int main( void )
 int main( int argc, char *argv[] )
 {
     FILE *f;
-    int ret = 1, c;
+    int ret = 1;
+    unsigned c;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     size_t i;
     mbedtls_rsa_context rsa;