diff --git a/libheif/plugins/decoder_openh264.cc b/libheif/plugins/decoder_openh264.cc
index a3eb6c60ca..163331da9d 100644
--- a/libheif/plugins/decoder_openh264.cc
+++ b/libheif/plugins/decoder_openh264.cc
@@ -130,6 +130,7 @@ struct heif_error openh264_decode_image(void* decoder_raw, struct heif_image** o
   std::vector<uint8_t> scdata;
 
   size_t idx = 0;
+  auto end = &indata[0];
   while (idx < indata.size()) {
     if (indata.size() - 4 < idx) {
       return kError_EOF;
@@ -162,7 +163,8 @@ struct heif_error openh264_decode_image(void* decoder_raw, struct heif_image** o
           scdata.push_back(0);
           scdata.push_back(3);
 
-          scdata.insert(scdata.end(), &indata[idx + 2], &indata[idx + i + 2]);
+          end = (&indata[idx + i + 1])+1;
+          scdata.insert(scdata.end(), &indata[idx + 2], end);
           idx += i + 2;
           size -= (uint32_t)(i + 2);
           found_start_code_emulation = true;
@@ -174,7 +176,8 @@ struct heif_error openh264_decode_image(void* decoder_raw, struct heif_image** o
     }
 
     assert(size > 0);
-    scdata.insert(scdata.end(), &indata[idx], &indata[idx + size]);
+    end = (&indata[idx + size - 1])+1;
+    scdata.insert(scdata.end(), &indata[idx], end);
 
     idx += size;
   }