diff --git a/be/src/exprs/aggregate-functions-ir.cc b/be/src/exprs/aggregate-functions-ir.cc
index d5f946a..bf4446d 100644
--- a/be/src/exprs/aggregate-functions-ir.cc
+++ b/be/src/exprs/aggregate-functions-ir.cc
@@ -372,7 +372,11 @@
   return result;
 }
 
-struct DecimalAvgState {
+// We saw some failures on the release build because GCC was emitting an instruction
+// to operate on the int128_t that assumed the pointer was aligned (typically it isn't).
+// We mark the struct with a "packed" attribute, so that the compiler does not expect it
+// to be aligned. This should not have a negative performance impact on modern CPUs.
+struct __attribute__ ((__packed__)) DecimalAvgState {
   __int128_t sum_val16; // Always uses max precision decimal.
   int64_t count;
 };
diff --git a/fe/src/main/java/org/apache/impala/catalog/BuiltinsDb.java b/fe/src/main/java/org/apache/impala/catalog/BuiltinsDb.java
index 07699d3..e603fc6 100644
--- a/fe/src/main/java/org/apache/impala/catalog/BuiltinsDb.java
+++ b/fe/src/main/java/org/apache/impala/catalog/BuiltinsDb.java
@@ -40,7 +40,7 @@
   private static final int AVG_INTERMEDIATE_SIZE = 16;
 
   // Size in bytes of DecimalAvgState used for decimal avg().
-  private static final int DECIMAL_AVG_INTERMEDIATE_SIZE = 32;
+  private static final int DECIMAL_AVG_INTERMEDIATE_SIZE = 24;
 
   // Size in bytes of KnuthVarianceState used for stddev(), variance(), etc.
   private static final int STDDEV_INTERMEDIATE_SIZE = 24;
diff --git a/testdata/workloads/functional-query/queries/QueryTest/functions-ddl.test b/testdata/workloads/functional-query/queries/QueryTest/functions-ddl.test
index f629b37..22d7122 100644
--- a/testdata/workloads/functional-query/queries/QueryTest/functions-ddl.test
+++ b/testdata/workloads/functional-query/queries/QueryTest/functions-ddl.test
@@ -121,7 +121,7 @@
  FINALIZE_FN='_ZN6impala18AggregateFunctions11AvgFinalizeEPN10impala_udf15FunctionContextERKNS1_9StringValE'
 CREATE AGGREGATE FUNCTION _impala_builtins.avg(DECIMAL(*,*))
  RETURNS DECIMAL(*,*)
- INTERMEDIATE FIXED_UDA_INTERMEDIATE(32)
+ INTERMEDIATE FIXED_UDA_INTERMEDIATE(24)
  LOCATION 'null'
  UPDATE_FN='_ZN6impala18AggregateFunctions16DecimalAvgUpdateEPN10impala_udf15FunctionContextERKNS1_10DecimalValEPNS1_9StringValE'
  INIT_FN='_ZN6impala18AggregateFunctions14DecimalAvgInitEPN10impala_udf15FunctionContextEPNS1_9StringValE'