diff --git a/src/image.cpp b/src/image.cpp
index 620f1908..5d11a03b 100644
--- a/src/image.cpp
+++ b/src/image.cpp
@@ -72,6 +72,7 @@ EXIV2_RCSID("@(#) $Id$")
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <stdarg.h>
 #ifdef _MSC_VER
 # define S_ISREG(m)      (((m) & S_IFMT) == S_IFREG)
 #endif
diff --git a/src/pngimage.cpp b/src/pngimage.cpp
index 95431d05..ea073ef8 100644
--- a/src/pngimage.cpp
+++ b/src/pngimage.cpp
@@ -137,8 +137,8 @@ namespace Exiv2 {
                     chType[i-4]=cheaderBuf.pData_[i];
                 }
 
-                size_t      blen = 32   ;
-                size_t      dOff = dataOffset;
+                uint32_t    blen = 32   ;
+                uint32_t    dOff = dataOffset;
                 std::string dataString ;
 
                 if ( dataOffset > blen ) {
@@ -152,7 +152,7 @@ namespace Exiv2 {
 
                 // for XMP, back up and read the whole block
                 const char* key = "XML:com.adobe.xmp" ;
-                int       start = ::strlen(key);
+                size_t      start = ::strlen(key);
 
                 if ( option == kpsXMP && dataString.find(key)==0 ) {
 #if defined(_MSC_VER)