diff --git a/Source/FilteringFunctions/arm_fir_f32.c b/Source/FilteringFunctions/arm_fir_f32.c
index 3bc0ecb7..5a728e12 100644
--- a/Source/FilteringFunctions/arm_fir_f32.c
+++ b/Source/FilteringFunctions/arm_fir_f32.c
@@ -61,7 +61,7 @@
                    Samples in the state buffer are stored in the following order.
   @par
   <pre>
-      {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}
+      {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[n](==pSrc[0]), x[n+1](==pSrc[1]), ..., x[n+blockSize-1](==pSrc[blockSize-1])}
   </pre>
   @par
                    Note that the length of the state buffer exceeds the length of the coefficient array by <code>blockSize-1</code>.