diff --git a/backend/genesys_low.cc b/backend/genesys_low.cc
index 097375f..20dd3a4 100644
--- a/backend/genesys_low.cc
+++ b/backend/genesys_low.cc
@@ -49,6 +49,11 @@
 
 #include <vector>
 
+template <typename T>
+T safe_vec_addr(std::vector<T>& vec, int i)
+{
+  return vec.size() >= (unsigned long int)(i+1) ? vec[i] : (T)0;
+}
 
 Genesys_Device::~Genesys_Device()
 {
@@ -1209,17 +1214,17 @@ SANE_Status sanei_genesys_generate_gamma_buffer(Genesys_Device * dev,
                              dev->settings.brightness);
       for (int i = 0; i < size; i++)
         {
-          uint16_t value=rgamma[i];
+          uint16_t value = safe_vec_addr(rgamma, i);
           value=lut[value];
           gamma[i * 2 + size * 0 + 0] = value & 0xff;
           gamma[i * 2 + size * 0 + 1] = (value >> 8) & 0xff;
 
-          value=ggamma[i];
+          value = safe_vec_addr(ggamma, i);
           value=lut[value];
           gamma[i * 2 + size * 2 + 0] = value & 0xff;
           gamma[i * 2 + size * 2 + 1] = (value >> 8) & 0xff;
 
-          value=bgamma[i];
+          value = safe_vec_addr(bgamma, i);
           value=lut[value];
           gamma[i * 2 + size * 4 + 0] = value & 0xff;
           gamma[i * 2 + size * 4 + 1] = (value >> 8) & 0xff;
@@ -1229,15 +1234,15 @@ SANE_Status sanei_genesys_generate_gamma_buffer(Genesys_Device * dev,
     {
       for (int i = 0; i < size; i++)
         {
-          uint16_t value=rgamma[i];
+          uint16_t value = safe_vec_addr(rgamma, i);
           gamma[i * 2 + size * 0 + 0] = value & 0xff;
           gamma[i * 2 + size * 0 + 1] = (value >> 8) & 0xff;
 
-          value=ggamma[i];
+          value = safe_vec_addr(ggamma, i);
           gamma[i * 2 + size * 2 + 0] = value & 0xff;
           gamma[i * 2 + size * 2 + 1] = (value >> 8) & 0xff;
 
-          value=bgamma[i];
+          value = safe_vec_addr(bgamma, i);
           gamma[i * 2 + size * 4 + 0] = value & 0xff;
           gamma[i * 2 + size * 4 + 1] = (value >> 8) & 0xff;
         }