diff --git a/CHANGES.txt b/CHANGES.txt
index 18c0a9645d..d7a45363e8 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -8,6 +8,7 @@
    values (CASSANDRA-7792)
  * Fix ordering of static cells (CASSANDRA-7763)
 Merged from 2.0:
+ * Forbid re-adding dropped counter columns (CASSANDRA-7831)
  * Fix CFMetaData#isThriftCompatible() for PK-only tables (CASSANDRA-7832)
  * Always reject inequality on the partition key without token()
    (CASSANDRA-7722)
diff --git a/conf/cassandra-env.sh b/conf/cassandra-env.sh
index 43a121cfb2..4e8a2c6d4c 100644
--- a/conf/cassandra-env.sh
+++ b/conf/cassandra-env.sh
@@ -90,7 +90,7 @@ calculate_heap_sizes()
 
 java_ver_output=`"${JAVA:-java}" -version 2>&1`
 
-jvmver=`echo "$java_ver_output" | grep 'java version' | awk -F'"' 'NR==1 {print $2}'`
+jvmver=`echo "$java_ver_output" | grep '[openjdk|java] version' | awk -F'"' 'NR==1 {print $2}'`
 JVM_VERSION=${jvmver%_*}
 JVM_PATCH_VERSION=${jvmver#*_}
 
diff --git a/src/java/org/apache/cassandra/cql3/statements/AlterTableStatement.java b/src/java/org/apache/cassandra/cql3/statements/AlterTableStatement.java
index be28943408..f286f31fe6 100644
--- a/src/java/org/apache/cassandra/cql3/statements/AlterTableStatement.java
+++ b/src/java/org/apache/cassandra/cql3/statements/AlterTableStatement.java
@@ -108,6 +108,10 @@ public class AlterTableStatement extends SchemaAlteringStatement
                     }
                 }
 
+                // Cannot re-add a dropped counter column. See #7831.
+                if (meta.isCounter() && meta.getDroppedColumns().containsKey(columnName))
+                    throw new InvalidRequestException(String.format("Cannot re-add previously dropped counter column %s", columnName));
+
                 AbstractType<?> type = validator.getType();
                 if (type instanceof CollectionType)
                 {