diff --git a/src/sf_iov.c b/src/sf_iov.c
index 6aa65c4..598d763 100644
--- a/src/sf_iov.c
+++ b/src/sf_iov.c
@@ -52,6 +52,7 @@ int sf_iova_consume(SFDynamicIOVArray *iova, const int consume_len)
     iova->iov = iob;
     if (iova->cnt == 0) {
         struct iovec *last;
+
         last = iob - 1;
         last->iov_base = (char *)last->iov_base + last->iov_len;
         last->iov_len = 0;
@@ -68,7 +69,7 @@ int sf_iova_consume(SFDynamicIOVArray *iova, const int consume_len)
     return 0;
 }
 
-static inline void iova_slice(SFDynamicIOVArray *iova, const int slice_len)
+static inline int iova_slice(SFDynamicIOVArray *iova, const int slice_len)
 {
     struct iovec *iob;
     struct iovec *end;
@@ -88,7 +89,16 @@ static inline void iova_slice(SFDynamicIOVArray *iova, const int slice_len)
         }
     }
 
-    iova->cnt = (iob - iova->iov) + 1;
+    if (iob < end) {
+        iova->cnt = (iob - iova->iov) + 1;
+        return 0;
+    } else {
+        logError("file: "__FILE__", line: %d, "
+                "iov remain bytes: %d < slice length: %d",
+                __LINE__, bytes, slice_len);
+        iova->cnt = 0;
+        return EOVERFLOW;
+    }
 }
 
 int sf_iova_first_slice(SFDynamicIOVArray *iova, const int slice_len)
@@ -99,15 +109,14 @@ int sf_iova_first_slice(SFDynamicIOVArray *iova, const int slice_len)
         return result;
     }
 
-    iova_slice(iova, slice_len);
-    return 0;
+    return iova_slice(iova, slice_len);
 }
 
 int sf_iova_next_slice(SFDynamicIOVArray *iova,
         const int consume_len, const int slice_len)
 {
     struct iovec *last;
-    struct iovec *origin;
+    const struct iovec *origin;
     int remain_len;
     int result;
 
@@ -126,6 +135,5 @@ int sf_iova_next_slice(SFDynamicIOVArray *iova,
         }
     }
 
-    iova_slice(iova, slice_len);
-    return 0;
+    return iova_slice(iova, slice_len);
 }
diff --git a/src/sf_iov.h b/src/sf_iov.h
index 3e21ee9..1a2d5fa 100644
--- a/src/sf_iov.h
+++ b/src/sf_iov.h
@@ -26,7 +26,7 @@ typedef struct sf_dynamic_iov_array {
     struct iovec *ptr;
 
     struct {
-        struct iovec *iov;
+        const struct iovec *iov;
         int cnt;
     } input;
 
@@ -39,7 +39,7 @@ typedef struct sf_dynamic_iov_array {
     (iova).cnt = (iova).input.cnt = _cnt
 
 #define sf_iova_destroy(iova) \
-    if ((iova).iov != (iova).input.iov && \
+    if ((iova).iov != (struct iovec *)(iova).input.iov && \
             (iova).ptr != (iova).holder)  \
             free((iova).ptr)
 
@@ -49,7 +49,7 @@ extern "C" {
 
 static inline int sf_iova_check_alloc(SFDynamicIOVArray *iova)
 {
-    if (iova->iov == iova->input.iov) {
+    if (iova->iov == (struct iovec *)iova->input.iov) {
         if (iova->input.cnt <= SF_IOV_FIXED_SIZE) {
             iova->ptr = iova->holder;
         } else {