diff --git a/rtengine/dcraw.cc b/rtengine/dcraw.cc
index 2e93983b6..4d03989f8 100644
--- a/rtengine/dcraw.cc
+++ b/rtengine/dcraw.cc
@@ -10747,7 +10747,7 @@ canon_a5:
     } else if (!strncmp(model,"ALPHA",5) ||
 	       !strncmp(model,"DYNAX",5) ||
 	       !strncmp(model,"MAXXUM",6)) {
-      sprintf (model+20, "DYNAX %-10s", model+6+(model[0]=='M'));
+      snprintf (model+20, 20-(model[0]=='M'), "DYNAX %-10s", model+6+(model[0]=='M'));
       adobe_coeff (make, model+20);
       load_raw = &CLASS packed_load_raw;
     } else if (!strncmp(model,"DiMAGE G",8)) {
diff --git a/rtengine/rtthumbnail.cc b/rtengine/rtthumbnail.cc
index 26c1cd646..e30571c1a 100644
--- a/rtengine/rtthumbnail.cc
+++ b/rtengine/rtthumbnail.cc
@@ -53,20 +53,6 @@
 namespace
 {
 
-bool checkRawImageThumb (const rtengine::RawImage& raw_image)
-{
-    if (!raw_image.is_supportedThumb()) {
-        return false;
-    }
-
-    const ssize_t length =
-        fdata (raw_image.get_thumbOffset(), raw_image.get_file())[1] != 0xD8 && raw_image.is_ppmThumb()
-        ? raw_image.get_thumbWidth() * raw_image.get_thumbHeight() * (raw_image.get_thumbBPS() / 8) * 3
-        : raw_image.get_thumbLength();
-
-    return raw_image.get_thumbOffset() + length <= raw_image.get_file()->size;
-}
-
 /**
  * Apply the black level adjustments in the processing parameters.
  *
diff --git a/rtgui/options.cc b/rtgui/options.cc
index bdc595f5c..c06711d3b 100644
--- a/rtgui/options.cc
+++ b/rtgui/options.cc
@@ -1273,7 +1273,7 @@ void Options::readFromFile(Glib::ustring fname)
                 std::map<std::string, int> checkedExtensions;
 
                 if (parseExtensions.size() == parseExtensionsEnabled.size()) {
-                    for (auto i = 0; i < parseExtensions.size(); ++i) {
+                    for (unsigned i = 0; i < parseExtensions.size(); ++i) {
                         checkedExtensions[parseExtensions[i]] = parseExtensionsEnabled[i];
                     }
                 }
diff --git a/rtgui/thumbnail.cc b/rtgui/thumbnail.cc
index f5098ae6d..f03eaeccc 100644
--- a/rtgui/thumbnail.cc
+++ b/rtgui/thumbnail.cc
@@ -66,7 +66,7 @@ bool CPBDump(
     }
 
     // open the file in write mode
-    const std::unique_ptr<FILE, decltype(&std::fclose)> f(g_fopen(commFName.c_str (), "wt"), &std::fclose);
+    const std::unique_ptr<FILE, int (*)(FILE *)> f(g_fopen(commFName.c_str(), "wt"), &std::fclose);
 
     if (!f) {
         printf ("CPBDump(\"%s\") >>> Error: unable to open file with write access!\n", commFName.c_str());