diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index bf4e9b8..0ec8605 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -100,7 +100,7 @@
 int
 boot_magic_code(const uint32_t *magic)
 {
-    int i;
+    size_t i;
 
     if (memcmp(magic, boot_img_magic, BOOT_MAGIC_SZ) == 0) {
         return BOOT_MAGIC_GOOD;
@@ -413,7 +413,7 @@
     struct boot_swap_state slot0;
     struct boot_swap_state slot1;
     int rc;
-    int i;
+    size_t i;
 
     rc = boot_read_swap_state_by_id(FLASH_AREA_IMAGE_0, &slot0);
     if (rc) {
diff --git a/boot/bootutil/src/image_rsa.c b/boot/bootutil/src/image_rsa.c
index 88ec784..4d4ab1f 100644
--- a/boot/bootutil/src/image_rsa.c
+++ b/boot/bootutil/src/image_rsa.c
@@ -268,7 +268,7 @@
     end = cp + *bootutil_keys[key_id].len;
 
     rc = bootutil_parse_rsakey(&ctx, &cp, end);
-    if (rc || slen != ctx.len) {
+    if (rc || (size_t)slen != ctx.len) {
         mbedtls_rsa_free(&ctx);
         return rc;
     }
diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index 9a921d8..b5e5c4a 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -149,7 +149,7 @@
     struct boot_swap_state state_scratch;
     struct boot_swap_state state_slot0;
     int rc;
-    int i;
+    size_t i;
     uint8_t source;
 
     rc = boot_read_swap_state_by_id(FLASH_AREA_IMAGE_0, &state_slot0);
@@ -1068,7 +1068,7 @@
     uint32_t sz;
     int first_sector_idx;
     int last_sector_idx;
-    int swap_idx;
+    uint32_t swap_idx;
     struct image_header *hdr;
     uint32_t size;
     uint32_t copy_size;