diff --git a/rtengine/imagedata.cc b/rtengine/imagedata.cc
index f8e257ddc..8dfd90ab3 100644
--- a/rtengine/imagedata.cc
+++ b/rtengine/imagedata.cc
@@ -46,8 +46,6 @@ ImageMetaData* ImageMetaData::fromFile (const Glib::ustring& fname, RawMetaDataL
 
 ImageData::ImageData (Glib::ustring fname, RawMetaDataLocation* ri) : iso_speed(0), aperture(0.), shutter(0.)
 {
-
-    size_t dotpos = fname.find_last_of ('.');
     root = nullptr;
     iptc = nullptr;
 
@@ -72,7 +70,7 @@ ImageData::ImageData (Glib::ustring fname, RawMetaDataLocation* ri) : iso_speed(
             fclose (f);
             extractInfo ();
         }
-    } else if ((dotpos < fname.size() - 3 && !fname.casefold().compare (dotpos, 4, ".jpg")) || (dotpos < fname.size() - 4 && !fname.casefold().compare (dotpos, 5, ".jpeg"))) {
+    } else if (hasJpegExtension(fname)) {
         FILE* f = g_fopen (fname.c_str (), "rb");
 
         if (f) {
@@ -83,7 +81,7 @@ ImageData::ImageData (Glib::ustring fname, RawMetaDataLocation* ri) : iso_speed(
             iptc = iptc_data_new_from_jpeg_file (ff);
             fclose (ff);
         }
-    } else if ((dotpos < fname.size() - 3 && !fname.casefold().compare (dotpos, 4, ".tif")) || (dotpos < fname.size() - 4 && !fname.casefold().compare (dotpos, 5, ".tiff"))) {
+    } else if (hasTiffExtension(fname)) {
         FILE* f = g_fopen (fname.c_str (), "rb");
 
         if (f) {
diff --git a/rtengine/imageio.cc b/rtengine/imageio.cc
index e886dabce..59f7cf541 100644
--- a/rtengine/imageio.cc
+++ b/rtengine/imageio.cc
@@ -1441,19 +1441,11 @@ void png_flush(png_structp png_ptr)
 int ImageIO::load (Glib::ustring fname)
 {
 
-    size_t lastdot = fname.find_last_of ('.');
-
-    if( Glib::ustring::npos == lastdot ) {
-        return IMIO_FILETYPENOTSUPPORTED;
-    }
-
-    if (!fname.casefold().compare (lastdot, 4, ".png")) {
+    if (hasPngExtension(fname)) {
         return loadPNG (fname);
-    } else if (!fname.casefold().compare (lastdot, 4, ".jpg") ||
-               !fname.casefold().compare (lastdot, 5, ".jpeg")) {
+    } else if (hasJpegExtension(fname)) {
         return loadJPEG (fname);
-    } else if (!fname.casefold().compare (lastdot, 4, ".tif") ||
-               !fname.casefold().compare (lastdot, 5, ".tiff")) {
+    } else if (hasTiffExtension(fname)) {
         return loadTIFF (fname);
     } else {
         return IMIO_FILETYPENOTSUPPORTED;
@@ -1462,20 +1454,11 @@ int ImageIO::load (Glib::ustring fname)
 
 int ImageIO::save (Glib::ustring fname)
 {
-
-    size_t lastdot = fname.find_last_of ('.');
-
-    if( Glib::ustring::npos == lastdot ) {
-        return IMIO_FILETYPENOTSUPPORTED;
-    }
-
-    if (!fname.casefold().compare (lastdot, 4, ".png")) {
+    if (hasPngExtension(fname)) {
         return savePNG (fname);
-    } else if (!fname.casefold().compare (lastdot, 4, ".jpg") ||
-               !fname.casefold().compare (lastdot, 5, ".jpeg")) {
+    } else if (hasJpegExtension(fname)) {
         return saveJPEG (fname);
-    } else if (!fname.casefold().compare (lastdot, 4, ".tif") ||
-               !fname.casefold().compare (lastdot, 5, ".tiff")) {
+    } else if (hasTiffExtension(fname)) {
         return saveTIFF (fname);
     } else {
         return IMIO_FILETYPENOTSUPPORTED;
diff --git a/rtengine/stdimagesource.cc b/rtengine/stdimagesource.cc
index 2eda4b512..ac911aaa7 100644
--- a/rtengine/stdimagesource.cc
+++ b/rtengine/stdimagesource.cc
@@ -74,27 +74,19 @@ void StdImageSource::getSampleFormat (const Glib::ustring &fname, IIOSampleForma
     sFormat = IIOSF_UNKNOWN;
     sArrangement = IIOSA_UNKNOWN;
 
-    size_t lastdot = fname.find_last_of ('.');
-
-    if( Glib::ustring::npos == lastdot ) {
-        return;
-    }
-
-    if (!fname.casefold().compare (lastdot, 4, ".jpg") ||
-            !fname.casefold().compare (lastdot, 5, ".jpeg")) {
+    if (hasJpegExtension(fname)) {
         // For now, png and jpeg files are converted to unsigned short by the loader itself,
         // but there should be functions that read the sample format first, like the TIFF case below
         sFormat = IIOSF_UNSIGNED_CHAR;
         sArrangement = IIOSA_CHUNKY;
         return;
-    } else if (!fname.casefold().compare (lastdot, 4, ".png")) {
+    } else if (hasPngExtension(fname)) {
         int result = ImageIO::getPNGSampleFormat (fname, sFormat, sArrangement);
 
         if (result == IMIO_SUCCESS) {
             return;
         }
-    } else if (!fname.casefold().compare (lastdot, 4, ".tif") ||
-               !fname.casefold().compare (lastdot, 5, ".tiff")) {
+    } else if (hasTiffExtension(fname)) {
         int result = ImageIO::getTIFFSampleFormat (fname, sFormat, sArrangement);
 
         if (result == IMIO_SUCCESS) {
diff --git a/rtengine/utils.cc b/rtengine/utils.cc
index b862e290f..f5b3e496b 100644
--- a/rtengine/utils.cc
+++ b/rtengine/utils.cc
@@ -29,7 +29,7 @@ using namespace std;
 namespace rtengine
 {
 
-void poke255_uc(unsigned char* &dest, unsigned char r, unsigned char g, unsigned char b)
+void poke255_uc(unsigned char*& dest, unsigned char r, unsigned char g, unsigned char b)
 {
 #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__
     *(dest++) = b;
@@ -44,7 +44,7 @@ void poke255_uc(unsigned char* &dest, unsigned char r, unsigned char g, unsigned
 #endif
 }
 
-void poke01_d(unsigned char* &dest, double r, double g, double b)
+void poke01_d(unsigned char*& dest, double r, double g, double b)
 {
 #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__
     *(dest++) = (unsigned char)(b * 255.);
@@ -59,7 +59,7 @@ void poke01_d(unsigned char* &dest, double r, double g, double b)
 #endif
 }
 
-void poke01_f(unsigned char* &dest, float r, float g, float b)
+void poke01_f(unsigned char*& dest, float r, float g, float b)
 {
 #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__
     *(dest++) = (unsigned char)(b * 255.f);
@@ -74,9 +74,8 @@ void poke01_f(unsigned char* &dest, float r, float g, float b)
 #endif
 }
 
-void bilinearInterp (const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh)
+void bilinearInterp(const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh)
 {
-
     int ix = 0;
 
     for (int i = 0; i < dh; i++) {
@@ -132,9 +131,8 @@ void bilinearInterp (const unsigned char* src, int sw, int sh, unsigned char* ds
     }
 }
 
-void nearestInterp (const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh)
+void nearestInterp(const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh)
 {
-
     int ix = 0;
 
     for (int i = 0; i < dh; i++) {
@@ -150,9 +148,8 @@ void nearestInterp (const unsigned char* src, int sw, int sh, unsigned char* dst
     }
 }
 
-void rotate (unsigned char* img, int& w, int& h, int deg)
+void rotate(unsigned char* img, int& w, int& h, int deg)
 {
-
     if (deg == 0) {
         return;
     }
@@ -186,13 +183,12 @@ void rotate (unsigned char* img, int& w, int& h, int deg)
                 rotated[3 * (w * (h - i - 1) + w - j - 1) + 2] = img[ix++];
             }
 
-    memcpy (img, rotated, 3 * w * h);
-    delete [] rotated;
+    memcpy(img, rotated, 3 * w * h);
+    delete[] rotated;
 }
 
-void hflip (unsigned char* img, int w, int h)
+void hflip(unsigned char* img, int w, int h)
 {
-
     unsigned char* flipped = new unsigned char[3 * w * h];
     int ix = 0;
 
@@ -203,13 +199,12 @@ void hflip (unsigned char* img, int w, int h)
             flipped[3 * (w * i + w - 1 - j) + 2] = img[ix++];
         }
 
-    memcpy (img, flipped, 3 * w * h);
-    delete [] flipped;
+    memcpy(img, flipped, 3 * w * h);
+    delete[] flipped;
 }
 
-void vflip (unsigned char* img, int w, int h)
+void vflip(unsigned char* img, int w, int h)
 {
-
     unsigned char* flipped = new unsigned char[3 * w * h];
     int ix = 0;
 
@@ -220,10 +215,34 @@ void vflip (unsigned char* img, int w, int h)
             flipped[3 * (w * (h - 1 - i) + j) + 2] = img[ix++];
         }
 
-    memcpy (img, flipped, 3 * w * h);
-    delete [] flipped;
+    memcpy(img, flipped, 3 * w * h);
+    delete[] flipped;
+}
+
+Glib::ustring getFileExtension(const Glib::ustring& filename)
+{
+    const Glib::ustring::size_type lastdot_pos = filename.find_last_of('.');
+    return
+        lastdot_pos != Glib::ustring::npos
+            ? filename.substr(lastdot_pos + 1).lowercase()
+            : Glib::ustring();
+}
+
+bool hasJpegExtension(const Glib::ustring& filename)
+{
+   const Glib::ustring extension = getFileExtension(filename);
+   return extension == "jpg" || extension == "jpeg";
+}
+
+bool hasTiffExtension(const Glib::ustring& filename)
+{
+   const Glib::ustring extension = getFileExtension(filename);
+   return extension == "tif" || extension == "tiff";
+}
+
+bool hasPngExtension(const Glib::ustring& filename)
+{
+   return getFileExtension(filename) == "png";
 }
 
 }
-
-
diff --git a/rtengine/utils.h b/rtengine/utils.h
index c46999219..b2c1d16a8 100644
--- a/rtengine/utils.h
+++ b/rtengine/utils.h
@@ -19,22 +19,23 @@
 #pragma once
 
 #include <type_traits>
+#include <glibmm/ustring.h>
 
 namespace rtengine
 {
 
-// update a point of a Cairo::Surface by accessing the raw data
-void poke255_uc(unsigned char* &dest, unsigned char r, unsigned char g, unsigned char b);
-// update a point of a Cairo::Surface by accessing the raw data
-void poke01_d(unsigned char* &dest, double r, double g, double b);
-// update a point of a Cairo::Surface by accessing the raw data
-void poke01_f(unsigned char* &dest, float r, float g, float b);
+// Update a point of a Cairo::Surface by accessing the raw data
+void poke255_uc(unsigned char*& dest, unsigned char r, unsigned char g, unsigned char b);
+// Update a point of a Cairo::Surface by accessing the raw data
+void poke01_d(unsigned char*& dest, double r, double g, double b);
+// Update a point of a Cairo::Surface by accessing the raw data
+void poke01_f(unsigned char*& dest, float r, float g, float b);
 
-void bilinearInterp (const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh);
-void nearestInterp (const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh);
-void rotate (unsigned char* img, int& w, int& h, int deg);
-void hflip (unsigned char* img, int w, int h);
-void vflip (unsigned char* img, int w, int h);
+void bilinearInterp(const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh);
+void nearestInterp(const unsigned char* src, int sw, int sh, unsigned char* dst, int dw, int dh);
+void rotate(unsigned char* img, int& w, int& h, int deg);
+void hflip(unsigned char* img, int w, int h);
+void vflip(unsigned char* img, int w, int h);
 
 template<typename ENUM>
 typename std::underlying_type<ENUM>::type toUnderlying(ENUM value)
@@ -42,4 +43,13 @@ typename std::underlying_type<ENUM>::type toUnderlying(ENUM value)
     return static_cast<typename std::underlying_type<ENUM>::type>(value);
 }
 
+// Return lower case extension without the "." or "" if the given name contains no "."
+Glib::ustring getFileExtension(const Glib::ustring& filename);
+// Return true if file has .jpeg or .jpg extension (ignoring case)
+bool hasJpegExtension(const Glib::ustring& filename);
+// Return true if file has .tiff or .tif extension (ignoring case)
+bool hasTiffExtension(const Glib::ustring& filename);
+// Return true if file has .png extension (ignoring case)
+bool hasPngExtension(const Glib::ustring& filename);
+
 }
diff --git a/rtgui/profilestore.cc b/rtgui/profilestore.cc
index c80bbe388..ddb6782d4 100644
--- a/rtgui/profilestore.cc
+++ b/rtgui/profilestore.cc
@@ -269,7 +269,6 @@ int ProfileStore::findFolderId(const Glib::ustring &path)
   */
 const ProfileStoreEntry* ProfileStore::findEntryFromFullPathU(Glib::ustring path)
 {
-
     if (path.empty()) {
         return nullptr;
     }
@@ -278,12 +277,18 @@ const ProfileStoreEntry* ProfileStore::findEntryFromFullPathU(Glib::ustring path
         return internalDefaultEntry;
     }
 
-    size_t lastdot = path.find_last_of ('.');
+    // consistently apply casefold() to make sure dot position is correct
+    const Glib::ustring casefolded_path = path.casefold();
+    const Glib::ustring::size_type lastdot_pos = casefolded_path.find_last_of('.');
 
-    if (lastdot != Glib::ustring::npos && lastdot <= path.size() - 4 && !path.casefold().compare (lastdot, 4, paramFileExtension))
-        // removing the extension
+    if (
+        lastdot_pos != Glib::ustring::npos
+        && lastdot_pos <= casefolded_path.size() - 4
+        && !casefolded_path.compare(lastdot_pos, 4, paramFileExtension))
     {
-        path = path.substr(0, lastdot);
+        // removing the extension
+        // now use dot position without casefold()
+        path = path.substr(0, path.find_last_of('.'));
     }
 
     // dir separator may come from options file and may be \ or /, we convert them to G_DIR_SEPARATOR_S