diff --git a/src/Type.cc b/src/Type.cc
index cb595a4428..99debc3c9c 100644
--- a/src/Type.cc
+++ b/src/Type.cc
@@ -1094,16 +1094,42 @@ EnumType::~EnumType()
 		delete [] iter->first;
 	}
 
-bro_int_t EnumType::AddName(const string& module_name, const char* name, bool is_export) 
+// Note, we don't use Error() and SetError(( for EnumType because EnumTypes can 
+// be redefined, the location associated with it is ill-defined and might result
+// in error messaging with confusing line numbers. 
+void EnumType::AddName(const string& module_name, const char* name, bool is_export) 
+	{ 
+	/* implicit, auto-increment */
+	if ( counter < 0) 
+		{
+		error("cannot mix explicit enumerator assignment and implicit auto-increment");
+		return;
+		}
+	AddNameInternal(module_name, name, counter, is_export);
+	counter++;
+	}
+
+void EnumType::AddName(const string& module_name, const char* name, bro_int_t val, bool is_export) 
 	{
-	return AddName(module_name, name, counter, is_export);
+	/* explicit value specified */
+	error_t rv;
+	if ( counter > 0 )
+		{
+		error("cannot mix explicit enumerator assignment and implicit auto-increment");
+		return;
+		}
+	counter = -1; 
+	AddNameInternal(module_name, name, val, is_export);
 	}
 	
-bro_int_t EnumType::AddName(const string& module_name, const char* name, bro_int_t val, bool is_export)
+void EnumType::AddNameInternal(const string& module_name, const char* name, bro_int_t val, bool is_export)
 	{
 	ID *id;
 	if ( Lookup(val) )
-		return -1;
+		{
+		error("enumerator value in enumerated type definition already exists");
+		return;
+		}
 
 	id = lookup_ID(name, module_name.c_str());
 	if ( ! id )
@@ -1113,12 +1139,13 @@ bro_int_t EnumType::AddName(const string& module_name, const char* name, bro_int
 		id->SetEnumConst();
 		}
 	else
-		return -1; 
+		{
+		error("identifier or enumerator value in enumerated type definition already exists");
+		return;
+		}
 
 	string fullname = make_full_var_name(module_name.c_str(), name);
 	names[copy_string(fullname.c_str())] = val;
-	counter = val + 1;
-	return val;
 	}
 
 bro_int_t EnumType::Lookup(const string& module_name, const char* name)
diff --git a/src/Type.h b/src/Type.h
index 7865946a1d..dca122eadf 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -455,16 +455,12 @@ public:
 	EnumType();
 	~EnumType();
 
-	// The value of this name is next counter value, which is returned.
-	// A return value of -1 means that the identifier or the counter values
-	// already existed (and thus could not be used).
-	bro_int_t AddName(const string& module_name, const char* name, bool is_export);
+	// The value of this name is next counter value. The counter is incremented
+	void AddName(const string& module_name, const char* name, bool is_export);
 
-	// The value of this name is set to val, which is return. The counter will
-	// be updated, so the next name (without val) will have val+1
-	// A return value of -1 means that the identifier or val
-	// already existed (and thus could not be used).
-	bro_int_t AddName(const string& module_name, const char* name, bro_int_t val, bool is_export);
+	// The value of this name is set to val. The counter will
+	// be set to -1 to indicate that we are assigning explicit values 
+	void AddName(const string& module_name, const char* name, bro_int_t val, bool is_export);
 
 	// -1 indicates not found.
 	bro_int_t Lookup(const string& module_name, const char* name);
@@ -473,8 +469,16 @@ public:
 protected:
 	DECLARE_SERIAL(EnumType)
 
+	void AddNameInternal(const string& module_name, const char* name, bro_int_t val, bool is_export);
+
 	typedef std::map< const char*, bro_int_t, ltstr > NameMap;
 	NameMap names;
+	// counter is initialized to 0 and incremented on every implicit
+	// auto-increment name that gets added (thus its > 0 if auto-increment 
+	// is used). 
+	// If an explicit value is specified, the counter is set to -1
+	// This way counter can be used to prevent mixing of auto-increment 
+	// and explicit enumerator specification
 	bro_int_t counter;
 };
 
diff --git a/src/parse.y b/src/parse.y
index 4338f6d788..e9de07eb8f 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -594,8 +594,8 @@ enum_body_elem:
 			assert(cur_enum_type);
 			if ($3->Type()->Tag() != TYPE_COUNT)
 				error("enumerator is not a count constant");
-			if ( cur_enum_type->AddName(current_module, $1, $3->InternalUnsigned(), is_export) < 0 )
-				error("identifier or enumerator value in enumerated type definition already exists");
+			else 
+				cur_enum_type->AddName(current_module, $1, $3->InternalUnsigned(), is_export);
 			}
 	|	TOK_ID '=' '-' TOK_CONSTANT
 			{
@@ -609,8 +609,7 @@ enum_body_elem:
 			{
 			set_location(@1);
 			assert(cur_enum_type);
-			if ( cur_enum_type->AddName(current_module, $1, is_export) < 0 )
-				error("identifier  or enumerator value in enumerated type definition already exists");
+			cur_enum_type->AddName(current_module, $1, is_export);
 			}
 	;
 		
@@ -716,9 +715,10 @@ type:
 				$$ = 0;
 				}
 
-	|	TOK_ENUM '{' { parser_new_enum(); } enum_body '}'
+	|	TOK_ENUM '{' { set_location(@1); parser_new_enum(); } enum_body '}'
 				{
 				set_location(@1, @5);
+				$4->UpdateLocationEndInfo(@5);
 				$$ = $4;
 				}