diff --git a/stim/envi/bip.h b/stim/envi/bip.h
index a2d9b17..0d0cfd8 100644
--- a/stim/envi/bip.h
+++ b/stim/envi/bip.h
@@ -1477,7 +1477,7 @@ public:
 		unsigned long long jump_sample = ( (Z() - b1) + b0 ) * sizeof(T);
 
 		//distance between sample spectra in adjacent lines
-		unsigned long long jump_line = (X() - x1) * Z() * sizeof(T);
+		unsigned long long jump_line = ( X() - x1 + x0 ) * Z() * sizeof(T);
 
 
 		//unsigned long long sp = y0 * X() + x0;		//start pixel
--
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