diff --git a/examples/nvme/identify/identify.c b/examples/nvme/identify/identify.c
index 04d9620c8..df3994649 100644
--- a/examples/nvme/identify/identify.c
+++ b/examples/nvme/identify/identify.c
@@ -93,7 +93,7 @@ get_feature(struct nvme_controller *ctrlr, uint8_t fid)
 static void
 get_features(struct nvme_controller *ctrlr)
 {
-	int i;
+	size_t i;
 
 	uint8_t features_to_get[] = {
 		NVME_FEAT_ARBITRATION,
diff --git a/lib/nvme/nvme_ctrlr.c b/lib/nvme/nvme_ctrlr.c
index 86b5960fe..04dd98ce1 100644
--- a/lib/nvme/nvme_ctrlr.c
+++ b/lib/nvme/nvme_ctrlr.c
@@ -56,7 +56,8 @@ nvme_ctrlr_construct_io_qpairs(struct nvme_controller *ctrlr)
 {
 	struct nvme_qpair		*qpair;
 	union nvme_cap_lo_register	cap_lo;
-	int				i, num_entries, num_trackers, rc;
+	uint32_t			i, num_entries, num_trackers;
+	int				rc;
 
 	if (ctrlr->ioq != NULL) {
 		/*
@@ -112,7 +113,7 @@ nvme_ctrlr_construct_io_qpairs(struct nvme_controller *ctrlr)
 static void
 nvme_ctrlr_fail(struct nvme_controller *ctrlr)
 {
-	int i;
+	uint32_t i;
 
 	ctrlr->is_failed = true;
 	nvme_qpair_fail(&ctrlr->adminq);
@@ -261,7 +262,8 @@ nvme_ctrlr_enable(struct nvme_controller *ctrlr)
 int
 nvme_ctrlr_hw_reset(struct nvme_controller *ctrlr)
 {
-	int i, rc;
+	uint32_t i;
+	int rc;
 	union nvme_cc_register cc;
 
 	cc.raw = nvme_mmio_read_4(ctrlr, cc.raw);
@@ -396,7 +398,7 @@ nvme_ctrlr_create_qpairs(struct nvme_controller *ctrlr)
 {
 	struct nvme_completion_poll_status	status;
 	struct nvme_qpair			*qpair;
-	int					i;
+	uint32_t				i;
 
 	if (nvme_ctrlr_construct_io_qpairs(ctrlr)) {
 		nvme_printf(ctrlr, "nvme_ctrlr_construct_io_qpairs failed!\n");
@@ -687,7 +689,7 @@ nvme_ctrlr_construct(struct nvme_controller *ctrlr, void *devhandle)
 void
 nvme_ctrlr_destruct(struct nvme_controller *ctrlr)
 {
-	int	i;
+	uint32_t	i;
 
 	nvme_ctrlr_disable(ctrlr);
 	nvme_ctrlr_shutdown(ctrlr);
diff --git a/lib/nvme/nvme_ctrlr_cmd.c b/lib/nvme/nvme_ctrlr_cmd.c
index bf4232afb..5dddd3e63 100644
--- a/lib/nvme/nvme_ctrlr_cmd.c
+++ b/lib/nvme/nvme_ctrlr_cmd.c
@@ -261,12 +261,12 @@ nvme_ctrlr_cmd_get_error_page(struct nvme_controller *ctrlr,
 	nvme_assert(num_entries > 0, ("%s called with num_entries==0\n", __func__));
 
 	/* Controller's error log page entries is 0-based. */
-	nvme_assert(num_entries <= (ctrlr->cdata.elpe + 1),
+	nvme_assert(num_entries <= (ctrlr->cdata.elpe + 1u),
 		    ("%s called with num_entries=%d but (elpe+1)=%d\n", __func__,
 		     num_entries, ctrlr->cdata.elpe + 1));
 
-	if (num_entries > (ctrlr->cdata.elpe + 1))
-		num_entries = ctrlr->cdata.elpe + 1;
+	if (num_entries > (ctrlr->cdata.elpe + 1u))
+		num_entries = ctrlr->cdata.elpe + 1u;
 
 	nvme_ctrlr_cmd_get_log_page(ctrlr, NVME_LOG_ERROR,
 				    NVME_GLOBAL_NAMESPACE_TAG, payload, sizeof(*payload) * num_entries,
diff --git a/lib/nvme/nvme_impl.h b/lib/nvme/nvme_impl.h
index 8f7c06cbe..5ec623840 100644
--- a/lib/nvme/nvme_impl.h
+++ b/lib/nvme/nvme_impl.h
@@ -99,6 +99,7 @@ nvme_malloc(const char *tag, size_t size, unsigned align, uint64_t *phys_addr)
  * Return the physical address for the specified virtual address.
  */
 #define nvme_vtophys(buf)		vtophys(buf)
+#define NVME_VTOPHYS_ERROR		VTOPHYS_ERROR
 
 extern struct rte_mempool *request_mempool;
 
diff --git a/lib/nvme/nvme_qpair.c b/lib/nvme/nvme_qpair.c
index 8214dfdb3..94ec61e31 100644
--- a/lib/nvme/nvme_qpair.c
+++ b/lib/nvme/nvme_qpair.c
@@ -709,7 +709,7 @@ nvme_qpair_submit_request(struct nvme_qpair *qpair, struct nvme_request *req)
 		 */
 
 		phys_addr = nvme_vtophys(req->u.payload);
-		if (phys_addr == -1) {
+		if (phys_addr == NVME_VTOPHYS_ERROR) {
 			_nvme_fail_request_bad_vtophys(qpair, tr);
 			return;
 		}
@@ -731,7 +731,7 @@ nvme_qpair_submit_request(struct nvme_qpair *qpair, struct nvme_request *req)
 			while (cur_nseg < nseg) {
 				seg_addr = req->u.payload + cur_nseg * PAGE_SIZE - unaligned;
 				phys_addr = nvme_vtophys(seg_addr);
-				if (phys_addr == -1) {
+				if (phys_addr == NVME_VTOPHYS_ERROR) {
 					_nvme_fail_request_bad_vtophys(qpair, tr);
 					return;
 				}
diff --git a/lib/util/string.c b/lib/util/string.c
index 4acbab2bb..1c2b5f1a4 100644
--- a/lib/util/string.c
+++ b/lib/util/string.c
@@ -63,7 +63,7 @@ sprintf_alloc(const char *format, ...)
 		 * If vsnprintf() returned a count within our current buffer size, we are done.
 		 * The count does not include the \0 terminator, so rc == bufsize is not OK.
 		 */
-		if (rc >= 0 && rc < bufsize) {
+		if (rc >= 0 && (size_t)rc < bufsize) {
 			return buf;
 		}
 
diff --git a/mk/spdk.common.mk b/mk/spdk.common.mk
index 4b7c31fde..a069f5026 100644
--- a/mk/spdk.common.mk
+++ b/mk/spdk.common.mk
@@ -43,7 +43,7 @@ endif
 
 OS := $(shell uname)
 
-COMMON_CFLAGS = -g $(C_OPT) -Wall -Werror -fno-strict-aliasing -march=native -m64 -I$(SPDK_ROOT_DIR)/include
+COMMON_CFLAGS = -g $(C_OPT) -Wall -Wsign-compare -Werror -fno-strict-aliasing -march=native -m64 -I$(SPDK_ROOT_DIR)/include
 
 COMMON_CFLAGS += -Wformat -Wformat-security -Wformat-nonliteral
 
diff --git a/test/lib/memory/vtophys.c b/test/lib/memory/vtophys.c
index 1dfb0740b..7cbdf7e22 100644
--- a/test/lib/memory/vtophys.c
+++ b/test/lib/memory/vtophys.c
@@ -62,7 +62,7 @@ vtophys_negative_test()
 		if (p == NULL)
 			continue;
 
-		if (vtophys(p) != -1) {
+		if (vtophys(p) != VTOPHYS_ERROR) {
 			rc = -1;
 			printf("Err: VA=%p is mapped to a huge_page,\n", p);
 			free(p);
@@ -94,7 +94,7 @@ vtophys_positive_test()
 		if (p == NULL)
 			continue;
 
-		if (vtophys(p) == -1) {
+		if (vtophys(p) == VTOPHYS_ERROR) {
 			rc = -1;
 			printf("Err: VA=%p is not mapped to a huge_page,\n", p);
 			rte_free(p);
diff --git a/test/lib/nvme/unit/nvme_ctrlr_cmd_c/nvme_ctrlr_cmd_ut.c b/test/lib/nvme/unit/nvme_ctrlr_cmd_c/nvme_ctrlr_cmd_ut.c
index 77b9aecaa..d2eb9f570 100644
--- a/test/lib/nvme/unit/nvme_ctrlr_cmd_c/nvme_ctrlr_cmd_ut.c
+++ b/test/lib/nvme/unit/nvme_ctrlr_cmd_c/nvme_ctrlr_cmd_ut.c
@@ -108,7 +108,7 @@ void verify_get_feature_cmd(struct nvme_request *req)
 void verify_abort_cmd(struct nvme_request *req)
 {
 	CU_ASSERT(req->cmd.opc == NVME_OPC_ABORT);
-	CU_ASSERT(req->cmd.cdw10 == ((abort_cid << 16) | abort_sqid));
+	CU_ASSERT(req->cmd.cdw10 == (((uint32_t)abort_cid << 16) | abort_sqid));
 }
 
 void verify_io_raw_cmd(struct nvme_request *req)
diff --git a/test/lib/nvme/unit/nvme_impl.h b/test/lib/nvme/unit/nvme_impl.h
index 1a3c14199..da131d9ce 100644
--- a/test/lib/nvme/unit/nvme_impl.h
+++ b/test/lib/nvme/unit/nvme_impl.h
@@ -65,6 +65,8 @@ do							\
 	while (0)
 
 uint64_t nvme_vtophys(void *buf);
+#define NVME_VTOPHYS_ERROR	(0xFFFFFFFFFFFFFFFFULL)
+
 #define nvme_alloc_request(bufp)	\
 do					\
 	{				\
diff --git a/test/lib/nvme/unit/nvme_ns_cmd_c/nvme_ns_cmd_ut.c b/test/lib/nvme/unit/nvme_ns_cmd_c/nvme_ns_cmd_ut.c
index 40dd2ac27..a0ac9632f 100644
--- a/test/lib/nvme/unit/nvme_ns_cmd_c/nvme_ns_cmd_ut.c
+++ b/test/lib/nvme/unit/nvme_ns_cmd_c/nvme_ns_cmd_ut.c
@@ -347,7 +347,7 @@ test_nvme_ns_cmd_deallocate(void)
 	nvme_ns_cmd_deallocate(&ns, payload, num_ranges, cb_fn, cb_arg);
 	CU_ASSERT(g_request->cmd.opc == NVME_OPC_DATASET_MANAGEMENT);
 	CU_ASSERT(g_request->cmd.nsid == ns.id);
-	CU_ASSERT(g_request->cmd.cdw10 == num_ranges - 1);
+	CU_ASSERT(g_request->cmd.cdw10 == num_ranges - 1u);
 	CU_ASSERT(g_request->cmd.cdw11 == NVME_DSM_ATTR_DEALLOCATE);
 	free(payload);
 	nvme_free_request(g_request);