diff --git a/include/sys/math_extras.h b/include/sys/math_extras.h
index 43256151ee6198..bef9a78a6bbecb 100644
--- a/include/sys/math_extras.h
+++ b/include/sys/math_extras.h
@@ -28,6 +28,7 @@
  * true if the operation overflowed.
  */
 /**@{*/
+static bool u16_add_overflow(u16_t a, u16_t b, u16_t *result);
 static bool u32_add_overflow(u32_t a, u32_t b, u32_t *result);
 static bool u64_add_overflow(u64_t a, u64_t b, u64_t *result);
 static bool size_add_overflow(size_t a, size_t b, size_t *result);
@@ -40,6 +41,7 @@ static bool size_add_overflow(size_t a, size_t b, size_t *result);
  * true if the operation overflowed.
  */
 /**@{*/
+static bool u16_mul_overflow(u16_t a, u16_t b, u16_t *result);
 static bool u32_mul_overflow(u32_t a, u32_t b, u32_t *result);
 static bool u64_mul_overflow(u64_t a, u64_t b, u64_t *result);
 static bool size_mul_overflow(size_t a, size_t b, size_t *result);
diff --git a/include/sys/math_extras_impl.h b/include/sys/math_extras_impl.h
index 7aa0f48907ae48..022d0b5604c70f 100644
--- a/include/sys/math_extras_impl.h
+++ b/include/sys/math_extras_impl.h
@@ -29,6 +29,11 @@
 #endif
 
 #if use_builtin(__builtin_add_overflow)
+static inline bool u16_add_overflow(u16_t a, u16_t b, u16_t *result)
+{
+	return __builtin_add_overflow(a, b, result);
+}
+
 static inline bool u32_add_overflow(u32_t a, u32_t b, u32_t *result)
 {
 	return __builtin_add_overflow(a, b, result);
@@ -44,6 +49,15 @@ static inline bool size_add_overflow(size_t a, size_t b, size_t *result)
 	return __builtin_add_overflow(a, b, result);
 }
 #else /* !use_builtin(__builtin_add_overflow) */
+static inline bool u16_add_overflow(u16_t a, u16_t b, u16_t *result)
+{
+	u16_t c = a + b;
+
+	*result = c;
+
+	return c < a;
+}
+
 static inline bool u32_add_overflow(u32_t a, u32_t b, u32_t *result)
 {
 	u32_t c = a + b;
@@ -73,6 +87,11 @@ static inline bool size_add_overflow(size_t a, size_t b, size_t *result)
 #endif /* use_builtin(__builtin_add_overflow) */
 
 #if use_builtin(__builtin_mul_overflow)
+static inline bool u16_mul_overflow(u16_t a, u16_t b, u16_t *result)
+{
+	return __builtin_mul_overflow(a, b, result);
+}
+
 static inline bool u32_mul_overflow(u32_t a, u32_t b, u32_t *result)
 {
 	return __builtin_mul_overflow(a, b, result);
@@ -88,6 +107,15 @@ static inline bool size_mul_overflow(size_t a, size_t b, size_t *result)
 	return __builtin_mul_overflow(a, b, result);
 }
 #else /* !use_builtin(__builtin_mul_overflow) */
+static inline bool u16_mul_overflow(u16_t a, u16_t b, u16_t *result)
+{
+	u16_t c = a * b;
+
+	*result = c;
+
+	return a != 0 && (c / a) != b;
+}
+
 static inline bool u32_mul_overflow(u32_t a, u32_t b, u32_t *result)
 {
 	u32_t c = a * b;
diff --git a/subsys/net/lib/coap/coap.c b/subsys/net/lib/coap/coap.c
index a4bcff36643601..ac0661919b2e1e 100644
--- a/subsys/net/lib/coap/coap.c
+++ b/subsys/net/lib/coap/coap.c
@@ -17,6 +17,7 @@ LOG_MODULE_REGISTER(net_coap, CONFIG_COAP_LOG_LEVEL);
 
 #include <zephyr/types.h>
 #include <sys/byteorder.h>
+#include <sys/math_extras.h>
 
 #include <net/net_ip.h>
 #include <net/net_core.h>
@@ -469,7 +470,9 @@ static int parse_option(u8_t *data, u16_t offset, u16_t *pos,
 			return -EINVAL;
 		}
 
-		*opt_len += hdr_len;
+		if (u16_add_overflow(*opt_len, hdr_len, opt_len)) {
+			return -EINVAL;
+		}
 	}
 
 	if (len > COAP_OPTION_NO_EXT) {
@@ -480,11 +483,15 @@ static int parse_option(u8_t *data, u16_t offset, u16_t *pos,
 			return -EINVAL;
 		}
 
-		*opt_len += hdr_len;
+		if (u16_add_overflow(*opt_len, hdr_len, opt_len)) {
+			return -EINVAL;
+		}
 	}
 
-	*opt_delta += delta;
-	*opt_len += len;
+	if (u16_add_overflow(*opt_delta, delta, opt_delta) ||
+	    u16_add_overflow(*opt_len, len, opt_len)) {
+		return -EINVAL;
+	}
 
 	if (r == 0) {
 		if (len == 0U) {
@@ -519,7 +526,10 @@ static int parse_option(u8_t *data, u16_t offset, u16_t *pos,
 			return -EINVAL;
 		}
 	} else {
-		*pos += len;
+		if (u16_add_overflow(*pos, len, pos)) {
+			return -EINVAL;
+		}
+
 		r = max_len - *pos;
 	}