diff --git a/include/exiv2/value.hpp b/include/exiv2/value.hpp
index 2078c6bdbb..b7d76fefde 100644
--- a/include/exiv2/value.hpp
+++ b/include/exiv2/value.hpp
@@ -1659,11 +1659,13 @@ namespace Exiv2 {
         ok_ = true;
         return static_cast<long>(value_[n]);
     }
+// #55 crash when value_[n].first == LONG_MIN
+#define LARGE_INT 1000000
     // Specialization for rational
     template<>
     inline long ValueType<Rational>::toLong(long n) const
     {
-        ok_ = (value_[n].second != 0 && INT_MIN < value_[n].first && value_[n].first < INT_MAX );
+        ok_ = (value_[n].second != 0 && -LARGE_INT < value_[n].first && value_[n].first < LARGE_INT);
         if (!ok_) return 0;
         return value_[n].first / value_[n].second;
     }
@@ -1671,7 +1673,7 @@ namespace Exiv2 {
     template<>
     inline long ValueType<URational>::toLong(long n) const
     {
-        ok_ = (value_[n].second != 0);
+        ok_ = (value_[n].second != 0 && value_[n].first < LARGE_INT);
         if (!ok_) return 0;
         return value_[n].first / value_[n].second;
     }
diff --git a/src/basicio.cpp b/src/basicio.cpp
index 28aa454db6..9c5c04cafc 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -990,6 +990,7 @@ namespace Exiv2 {
     DataBuf FileIo::read(long rcount)
     {
         assert(p_->fp_ != 0);
+        if ( (size_t) rcount > size() ) throw Error(57);
         DataBuf buf(rcount);
         long readCount = read(buf.pData_, buf.size_);
         buf.size_ = readCount;
diff --git a/src/bigtiffimage.cpp b/src/bigtiffimage.cpp
index 7c64a0d5cc..d5813ad006 100644
--- a/src/bigtiffimage.cpp
+++ b/src/bigtiffimage.cpp
@@ -226,14 +226,20 @@ namespace Exiv2
                                                   : is8ByteType(type)  ? 8
                                                   : 1;
 
-                            DataBuf buf(size * count + pad);
+                			// #55 memory allocation crash test/data/POC8
+                			long long allocate = (long long) (size*count + pad);
+                			if ( allocate > (long long) io.size() ) {
+                    			throw Error(57);
+                			}
+
+                            DataBuf buf(allocate);
 
                             const uint64_t offset = header_.format() == Header::StandardTiff?
                                     byteSwap4(data, 0, doSwap_):
                                     byteSwap8(data, 0, doSwap_);
 
                             // big data? Use 'data' as pointer to real data
-                            const bool usePointer = count*size > dataSize_;
+                            const bool usePointer = (size_t) count*size > (size_t) dataSize_;
 
                             if ( usePointer )                          // read into buffer
                             {
diff --git a/src/error.cpp b/src/error.cpp
index 6ca8917d9a..e90a9c0ac8 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -106,8 +106,9 @@ namespace {
         { 52, N_("%1 has invalid XMP value type `%2'") }, // %1=key, %2=value type
         { 53, N_("Not a valid ICC Profile") },
         { 54, N_("Not valid XMP") },
-        { 55, N_("tiff directory length is too large") }, 
+        { 55, N_("tiff directory length is too large") },
         { 56, N_("invalid type value detected in Image::printIFDStructure") },
+        { 57, N_("invalid memory allocation request") },
     };
 
 }
diff --git a/src/image.cpp b/src/image.cpp
index 0fe268d87b..4c6dd07a78 100644
--- a/src/image.cpp
+++ b/src/image.cpp
@@ -400,7 +400,13 @@ namespace Exiv2 {
                                 ;
 
                 // if ( offset > io.size() ) offset = 0; // Denial of service?
-                DataBuf  buf(size*count + pad+20);  // allocate a buffer
+
+                // #55 memory allocation crash test/data/POC8
+                long long allocate = (long long) (size*count + pad+20);
+                if ( allocate > (long long) io.size() ) {
+                    throw Error(57);
+                }
+                DataBuf  buf(allocate);  // allocate a buffer
                 std::memcpy(buf.pData_,dir.pData_+8,4);  // copy dir[8:11] into buffer (short strings)
                 const bool bOffsetIsPointer = count*size > 4;
 
diff --git a/test/data/bugfixes-test.out b/test/data/bugfixes-test.out
index 3bcd776b78..6304c0fcbf 100644
Binary files a/test/data/bugfixes-test.out and b/test/data/bugfixes-test.out differ