diff --git a/src/cairo_context.cpp b/src/cairo_context.cpp
index cf04116f3..413f76032 100644
--- a/src/cairo_context.cpp
+++ b/src/cairo_context.cpp
@@ -436,7 +436,7 @@ void cairo_context::add_text(text_path const& path,
 
     path.rewind();
 
-    for (int iii = 0; iii < path.num_nodes(); iii++)
+    for (std::size_t iii = 0; iii < path.num_nodes(); ++iii)
     {
         char_info_ptr c;
         double x, y, angle;
@@ -470,7 +470,7 @@ void cairo_context::add_text(text_path const& path,
 
     path.rewind();
 
-    for (int iii = 0; iii < path.num_nodes(); iii++)
+    for (std::size_t iii = 0; iii < path.num_nodes(); ++iii)
     {
         char_info_ptr c;
         double x, y, angle;
diff --git a/src/font_engine_freetype.cpp b/src/font_engine_freetype.cpp
index 9917de86c..75669d5f3 100644
--- a/src/font_engine_freetype.cpp
+++ b/src/font_engine_freetype.cpp
@@ -545,7 +545,7 @@ box2d<double> text_renderer<T>::prepare_glyphs(text_path const& path)
     bbox.xMin = bbox.yMin = 32000;  // Initialize these so we can tell if we
     bbox.xMax = bbox.yMax = -32000; // properly grew the bbox later
 
-    for (int i = 0; i < path.num_nodes(); ++i)
+    for (std::size_t i = 0; i < path.num_nodes(); ++i)
     {
         char_info_ptr c;
         double x, y, angle;
diff --git a/src/jpeg_reader.cpp b/src/jpeg_reader.cpp
index 36aa63ac4..705f8e010 100644
--- a/src/jpeg_reader.cpp
+++ b/src/jpeg_reader.cpp
@@ -162,7 +162,7 @@ void jpeg_reader<T>::skip(j_decompress_ptr cinfo, long count)
     if (count <= 0) return; //A zero or negative skip count should be treated as a no-op.
     jpeg_stream_wrapper* wrap = reinterpret_cast<jpeg_stream_wrapper*>(cinfo->src);
 
-    if (wrap->manager.bytes_in_buffer > 0 && count < wrap->manager.bytes_in_buffer)
+    if (wrap->manager.bytes_in_buffer > 0 && count < static_cast<long>(wrap->manager.bytes_in_buffer))
     {
         wrap->manager.bytes_in_buffer -= count;
         wrap->manager.next_input_byte = &wrap->buffer[BUF_SIZE - wrap->manager.bytes_in_buffer];
diff --git a/src/png_reader.cpp b/src/png_reader.cpp
index 4a732b109..f328c7475 100644
--- a/src/png_reader.cpp
+++ b/src/png_reader.cpp
@@ -112,7 +112,8 @@ void png_reader<T>::png_read_data(png_structp png_ptr, png_bytep data, png_size_
 {
     input_stream * fin = reinterpret_cast<input_stream*>(png_get_io_ptr(png_ptr));
     fin->read(reinterpret_cast<char*>(data), length);
-    if (fin->gcount() != length)
+    std::streamsize read_count = fin->gcount();
+    if (read_count < 0 || static_cast<png_size_t>(read_count) != length)
     {
         png_error(png_ptr, "Read Error");
     }