diff --git a/src/statistics/rta_histogram.c b/src/statistics/rta_histogram.c
index 5171f95..d1c1fbc 100644
--- a/src/statistics/rta_histogram.c
+++ b/src/statistics/rta_histogram.c
@@ -140,7 +140,7 @@ void rta_histogram_weighted_stride (rta_histogram_params_t *self,
   }
 
   /* calculate histogram */
-  for (i = 0; i < i_size * i_stride; i += i_stride, weightptr += weightstride)
+  for (i = 0; i < i_size * i_stride; i += i_stride, weights += w_stride)
   {
     /* find bin index */
     int ind = (input[i] - self->lo) * xfact;
@@ -151,7 +151,7 @@ void rta_histogram_weighted_stride (rta_histogram_params_t *self,
     if (ind >= self->nhist)
       ind = self->nhist - 1;
 
-    output[ind * out_stride] += *weightptr;           
+    output[ind * out_stride] += *weights;           
   }
 
   // normalise histogram  
diff --git a/src/statistics/rta_histogram.h b/src/statistics/rta_histogram.h
index 73e8bbe..6bda676 100644
--- a/src/statistics/rta_histogram.h
+++ b/src/statistics/rta_histogram.h
@@ -41,6 +41,7 @@
 #define _RTA_HISTOGRAM_H_ 1
 
 #include "rta.h"
+#include <stdbool.h>	/* to get bool type in C99 */
 
 #ifdef __cplusplus
 extern "C" {
@@ -70,7 +71,7 @@ void rta_histogram_init (rta_histogram_params_t *self);
  * @param i_size	number of input elements
  * @param output	pointer to output data (at least params->nhist * out_stride elements)
  * @param out_stride	stride for output data
- * @param binout	NULL or pointer to bin index output data (at least params->nhist * bpf_stride elements)
+ * @param binout	NULL or pointer to bin index output data (at least params->nhist * bin_stride elements)
  * @param bin_stride	stride for bin index data
  */
 void rta_histogram_stride (rta_histogram_params_t *params,
@@ -90,7 +91,7 @@ void rta_histogram_stride (rta_histogram_params_t *params,
  * @param w_stride	stride for weights data
  * @param output	pointer to output data (at least params->nhist * out_stride elements)
  * @param out_stride	stride for output data
- * @param binout	NULL or pointer to bin index output data (at least params->nhist * bpf_stride elements)
+ * @param binout	NULL or pointer to bin index output data (at least params->nhist * bin_stride elements)
  * @param bin_stride	stride for bin index data
  */
 void rta_histogram_weighted_stride (rta_histogram_params_t *params,