diff --git a/src/image.cpp b/src/image.cpp
index 5d11a03b..5481732c 100644
--- a/src/image.cpp
+++ b/src/image.cpp
@@ -356,7 +356,7 @@ namespace Exiv2 {
     {
         std::string result;
 
-        int     need = fmt.size()*4;             // initial guess
+        int     need = (int) fmt.size()*4;       // initial guess
         char*   buffer = new char[need];         // allocate a buffer
         va_list ap;                              // variable arg list
 
@@ -366,6 +366,7 @@ namespace Exiv2 {
 
         if (need < 0) {                          // make buffer bigger
             delete[] buffer;
+			need   = -need ;
             buffer = new char[need+2];
             va_start(ap, fmt);
             need=vsnprintf(buffer, need, fmt.c_str(), ap);
diff --git a/src/tiffimage.cpp b/src/tiffimage.cpp
index 4c353eac..4e457a02 100644
--- a/src/tiffimage.cpp
+++ b/src/tiffimage.cpp
@@ -484,8 +484,8 @@ namespace Exiv2 {
                                    : count > 5              ? 5
                                    : count
                                    ;
-                    size_t pad     = isStringType(type) ? 1 : 0;
-                    size_t size    = isStringType(type) ? 1
+                    uint32_t pad   = isStringType(type) ? 1 : 0;
+                    uint32_t size  = isStringType(type) ? 1
                                    : is2ByteType(type)  ? 2
                                    : is4ByteType(type)  ? 4
                                    : 1