diff --git a/oqapy-iproc.h b/oqapy-iproc.h
index c52bb0b1..554112b3 100644
--- a/oqapy-iproc.h
+++ b/oqapy-iproc.h
@@ -52,7 +52,7 @@ private :
     Mat b_hist;
     Mat g_hist;
     Mat r_hist;
-    float c_hist[];
+    float* c_hist;
     void getColorHistogram();
     void setContrastStretching(int min, int max, int index);