diff --git a/os/hal/include/adc.h b/os/hal/include/adc.h
index 7c67e20d1..d7f918da3 100644
--- a/os/hal/include/adc.h
+++ b/os/hal/include/adc.h
@@ -228,18 +228,21 @@ typedef enum {
         /* Invokes the callback passing the 2nd half of the buffer.*/       \
         size_t half = (adcp)->depth / 2;                                    \
         size_t half_index = half * (adcp)->grpp->num_channels;              \
-        (adcp)->grpp->end_cb(adcp, (adcp)->samples + half_index, half);     \
+        (adcp)->grpp->end_cb(adcp, (adcp)->samples + half_index, (adcp)->depth - half);     \
       }                                                                     \
       else {                                                                \
         /* Invokes the callback passing the whole buffer.*/                 \
         (adcp)->grpp->end_cb(adcp, (adcp)->samples, (adcp)->depth);         \
       }                                                                     \
-      if ((adcp)->state == ADC_COMPLETE)                                    \
+      if ((adcp)->state == ADC_COMPLETE) {                                  \
         (adcp)->state = ADC_READY;                                          \
+        (adcp)->grpp = NULL;                                                \
+      }                                                                     \
     }                                                                       \
-    else                                                                    \
+    else {                                                                  \
       (adcp)->state = ADC_READY;                                            \
-    (adcp)->grpp = NULL;                                                    \
+      (adcp)->grpp = NULL;                                                  \
+    }                                                                       \
     _adc_wakeup_isr(adcp);                                                  \
   }                                                                         \
 }
diff --git a/readme.txt b/readme.txt
index e38983590..ad82294cf 100644
--- a/readme.txt
+++ b/readme.txt
@@ -85,6 +85,8 @@
 *****************************************************************************
 
 *** 2.5.2 ***
+- FIX: Fixed bug prevents calling adcStartConversionI() within ISR (bug
+  3605053)(backported to 2.4.4).
 - FIX: Fixed typo in platforms/STM32/can_lld.c (bug 3604657)(backported
   to 2.4.4).
 - FIX: Added board files and demo for "WaveShare Open STM32F4 207I-C / 407I-C".