diff --git a/library/rsa.c b/library/rsa.c
index 38c3dd6..1bf5d13 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1620,12 +1620,12 @@
         goto cleanup;
     }
 
-    if (ilen - (p - buf) > output_max_len) {
+    if (ilen - ((size_t) (p - buf)) > output_max_len) {
         ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE;
         goto cleanup;
     }
 
-    *olen = ilen - (p - buf);
+    *olen = ilen - ((size_t) (p - buf));
     if (*olen != 0) {
         memcpy(output, p, *olen);
     }
@@ -2191,7 +2191,7 @@
         return MBEDTLS_ERR_RSA_INVALID_PADDING;
     }
 
-    observed_salt_len = hash_start - p;
+    observed_salt_len = (size_t) (hash_start - p);
 
     if (expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
         observed_salt_len != (size_t) expected_salt_len) {