diff --git a/generator/nanopb_generator.py b/generator/nanopb_generator.py
index b572940..8eb351f 100755
--- a/generator/nanopb_generator.py
+++ b/generator/nanopb_generator.py
@@ -1231,7 +1231,6 @@
             return b''
 
         optional_only = copy.deepcopy(self.desc)
-        enums = {}
 
         # Remove fields without default values
         # The iteration is done in reverse order to avoid remove() messing up iteration.
@@ -1241,18 +1240,28 @@
             if parsed_field is None or parsed_field.allocation != 'STATIC':
                 optional_only.field.remove(field)
             elif (field.label == FieldD.LABEL_REPEATED or
-                  field.type == FieldD.TYPE_MESSAGE or
-                  not field.HasField('default_value')):
+                  field.type == FieldD.TYPE_MESSAGE):
                 optional_only.field.remove(field)
             elif hasattr(field, 'oneof_index') and field.HasField('oneof_index'):
                 optional_only.field.remove(field)
             elif field.type == FieldD.TYPE_ENUM:
                 # The partial descriptor doesn't include the enum type
                 # so we fake it with int64.
-                enums[field.name] = (names_from_type_name(field.type_name), field.default_value)
-                field.type = FieldD.TYPE_INT64
-                field.ClearField(str('default_value'))
-                field.ClearField(str('type_name'))
+                enumname = names_from_type_name(field.type_name)
+                enumtype = dependencies[str(enumname)]
+                if field.HasField('default_value'):
+                    defvals = [v for n,v in enumtype.values if n.parts[-1] == field.default_value]
+                else:
+                    # If no default is specified, the default is the first value.
+                    defvals = [v for n,v in enumtype.values]
+                if defvals and defvals[0] != 0:
+                    field.type = FieldD.TYPE_INT64
+                    field.default_value = str(defvals[0])
+                    field.ClearField(str('type_name'))
+                else:
+                    optional_only.field.remove(field)
+            elif not field.HasField('default_value'):
+                optional_only.field.remove(field)
 
         if len(optional_only.field) == 0:
             return b''
@@ -1273,14 +1282,6 @@
                 setattr(msg, field.name, float(field.default_value))
             elif field.type == FieldD.TYPE_BOOL:
                 setattr(msg, field.name, field.default_value == 'true')
-            elif field.name in enums:
-                # Lookup the enum default value
-                enumname = enums[field.name][0]
-                defval = enums[field.name][1]
-                enumtype = dependencies[str(enumname)]
-                defvals = [v for n,v in enumtype.values if n.parts[-1] == defval]
-                if defvals:
-                    setattr(msg, field.name, defvals[0])
             else:
                 setattr(msg, field.name, int(field.default_value))
 
diff --git a/tests/alltypes/alltypes.proto b/tests/alltypes/alltypes.proto
index df15d40..317b783 100644
--- a/tests/alltypes/alltypes.proto
+++ b/tests/alltypes/alltypes.proto
@@ -1,6 +1,12 @@
 syntax = "proto2";
 // package name placeholder
 
+enum NonZeroBasedEnum {
+    Two = 2;
+    Three = 3;
+    Four = 4;
+}
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];
@@ -127,6 +133,8 @@
         SubMessage oneof_msg1 = 60;
         EmptyMessage oneof_msg2 = 61;
     }
+
+    optional NonZeroBasedEnum opt_non_zero_based_enum = 62;
     
     // Check support for custom integer sizes
     required IntSizes req_intsizes = 96;
diff --git a/tests/alltypes/decode_alltypes.c b/tests/alltypes/decode_alltypes.c
index 1c49080..3b92614 100644
--- a/tests/alltypes/decode_alltypes.c
+++ b/tests/alltypes/decode_alltypes.c
@@ -158,6 +158,9 @@
         TEST(memcmp(alltypes.opt_fbytes, "4059", 4) == 0);
 
         TEST(alltypes.which_oneof == 0);
+
+        TEST(alltypes.has_opt_non_zero_based_enum == false);
+        TEST(alltypes.opt_non_zero_based_enum == NonZeroBasedEnum_Two);
     }
     else if (mode == 1)
     {
@@ -209,6 +212,9 @@
         TEST(alltypes.which_oneof == AllTypes_oneof_msg1_tag);
         TEST(strcmp(alltypes.oneof.oneof_msg1.substuff1, "4059") == 0);
         TEST(alltypes.oneof.oneof_msg1.substuff2 == 4059);
+
+        TEST(alltypes.has_opt_non_zero_based_enum == true);
+        TEST(alltypes.opt_non_zero_based_enum == NonZeroBasedEnum_Three);
     }
     else if (mode == 2)
     {
@@ -285,6 +291,8 @@
         TEST(alltypes.has_opt_fbytes == false);
 
         TEST(alltypes.which_oneof == 0);
+
+        TEST(alltypes.has_opt_non_zero_based_enum == false);
     }
     
     TEST(alltypes.end == 1099);
diff --git a/tests/alltypes/encode_alltypes.c b/tests/alltypes/encode_alltypes.c
index 00d2615..7f4ad2b 100644
--- a/tests/alltypes/encode_alltypes.c
+++ b/tests/alltypes/encode_alltypes.c
@@ -150,6 +150,9 @@
         alltypes.which_oneof = AllTypes_oneof_msg1_tag;
         strcpy(alltypes.oneof.oneof_msg1.substuff1, "4059");
         alltypes.oneof.oneof_msg1.substuff2 = 4059;
+
+        alltypes.has_opt_non_zero_based_enum = true;
+        alltypes.opt_non_zero_based_enum = NonZeroBasedEnum_Three;
     }
     
     alltypes.end = 1099;
diff --git a/tests/alltypes_callback/decode_alltypes_callback.c b/tests/alltypes_callback/decode_alltypes_callback.c
index 8079a04..71da215 100644
--- a/tests/alltypes_callback/decode_alltypes_callback.c
+++ b/tests/alltypes_callback/decode_alltypes_callback.c
@@ -450,6 +450,9 @@
 
         alltypes.oneof_msg1.funcs.decode = &read_submsg;
         alltypes.oneof_msg1.arg = &oneof_msg1;
+
+        alltypes.opt_non_zero_based_enum.funcs.decode = &read_varint;
+        alltypes.opt_non_zero_based_enum.arg = (void *)NonZeroBasedEnum_Three;
     }
     
     status = pb_decode(stream, AllTypes_fields, &alltypes);
diff --git a/tests/alltypes_callback/encode_alltypes_callback.c b/tests/alltypes_callback/encode_alltypes_callback.c
index 8f00b77..d123bf7 100644
--- a/tests/alltypes_callback/encode_alltypes_callback.c
+++ b/tests/alltypes_callback/encode_alltypes_callback.c
@@ -447,6 +447,9 @@
 
         alltypes.oneof_msg1.funcs.encode = &write_submsg;
         alltypes.oneof_msg1.arg = &oneof_msg1;
+
+        alltypes.opt_non_zero_based_enum.funcs.encode = &write_varint;
+        alltypes.opt_non_zero_based_enum.arg = (void *)NonZeroBasedEnum_Three;
     }
     
     alltypes.end.funcs.encode = &write_varint;
diff --git a/tests/alltypes_pointer/decode_alltypes_pointer.c b/tests/alltypes_pointer/decode_alltypes_pointer.c
index 5659012..f652b17 100644
--- a/tests/alltypes_pointer/decode_alltypes_pointer.c
+++ b/tests/alltypes_pointer/decode_alltypes_pointer.c
@@ -103,6 +103,8 @@
         TEST(alltypes.opt_fbytes        == NULL);
 
         TEST(alltypes.which_oneof       == 0);
+
+        TEST(alltypes.opt_non_zero_based_enum == NULL);
     }
     else
     {
@@ -134,6 +136,8 @@
         TEST(alltypes.which_oneof == AllTypes_oneof_msg1_tag);
         TEST(alltypes.oneof.oneof_msg1 && strcmp(alltypes.oneof.oneof_msg1->substuff1, "4059") == 0);
         TEST(alltypes.oneof.oneof_msg1->substuff2 && *alltypes.oneof.oneof_msg1->substuff2 == 4059);
+
+        TEST(alltypes.opt_non_zero_based_enum && *alltypes.opt_non_zero_based_enum == NonZeroBasedEnum_Three);
     }
     
     TEST(alltypes.req_limits->int32_min && *alltypes.req_limits->int32_min   == INT32_MIN);
diff --git a/tests/alltypes_pointer/encode_alltypes_pointer.c b/tests/alltypes_pointer/encode_alltypes_pointer.c
index ed780de..7f4b391 100644
--- a/tests/alltypes_pointer/encode_alltypes_pointer.c
+++ b/tests/alltypes_pointer/encode_alltypes_pointer.c
@@ -91,6 +91,8 @@
     static int32_t oneof_substuff = 4059;
     SubMessage  oneof_msg1        = {"4059", &oneof_substuff};
 
+    NonZeroBasedEnum opt_non_zero_based_enum = NonZeroBasedEnum_Three;
+
     /* Values for the Limits message. */
     static int32_t  int32_min  = INT32_MIN;
     static int32_t  int32_max  = INT32_MAX;
@@ -197,6 +199,8 @@
 
         alltypes.which_oneof = AllTypes_oneof_msg1_tag;
         alltypes.oneof.oneof_msg1 = &oneof_msg1;
+
+        alltypes.opt_non_zero_based_enum = &opt_non_zero_based_enum;
     }
     
     alltypes.end = &end;
diff --git a/tests/common_unittests/common_unittests.c b/tests/common_unittests/common_unittests.c
index faa8173..fabe67c 100644
--- a/tests/common_unittests/common_unittests.c
+++ b/tests/common_unittests/common_unittests.c
@@ -91,6 +91,8 @@
         TEST(iter.required_field_index == 19)
         TEST(iter.submessage_index == 7)
 
+        TEST(pb_field_iter_next(&iter) && iter.tag == 62 && iter.pData == &msg.opt_non_zero_based_enum && iter.pSize == &msg.has_opt_non_zero_based_enum)
+
         TEST(pb_field_iter_next(&iter) && iter.tag == 96 && iter.pData == &msg.req_intsizes && !iter.pSize)
         TEST(iter.required_field_index == 19)
         TEST(iter.submessage_index == 8)
diff --git a/tests/field_size_16/alltypes.proto b/tests/field_size_16/alltypes.proto
index c094421..9191ca0 100644
--- a/tests/field_size_16/alltypes.proto
+++ b/tests/field_size_16/alltypes.proto
@@ -1,5 +1,11 @@
 syntax = "proto2";
 
+enum NonZeroBasedEnum {
+    Two = 2;
+    Three = 3;
+    Four = 4;
+}
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];
@@ -127,6 +133,8 @@
         EmptyMessage oneof_msg2 = 10061;
     }
 
+    optional NonZeroBasedEnum opt_non_zero_based_enum = 10062;
+
     // Check support for custom integer sizes
     required IntSizes req_intsizes = 96;
 
diff --git a/tests/field_size_32/alltypes.proto b/tests/field_size_32/alltypes.proto
index 536fc2a..2ae0f1f 100644
--- a/tests/field_size_32/alltypes.proto
+++ b/tests/field_size_32/alltypes.proto
@@ -1,5 +1,11 @@
 syntax = "proto2";
 
+enum NonZeroBasedEnum {
+    Two = 2;
+    Three = 3;
+    Four = 4;
+}
+
 message SubMessage {
     required string substuff1 = 1 [default = "1"];
     required int32 substuff2 = 2 [default = 2];
@@ -127,6 +133,8 @@
         EmptyMessage oneof_msg2 = 10061;
     }
 
+    optional NonZeroBasedEnum opt_non_zero_based_enum = 10062;
+
     // Check support for custom integer sizes
     required IntSizes req_intsizes = 96;
 
diff --git a/tests/package_name/SConscript b/tests/package_name/SConscript
index 4afc503..071a3e8 100644
--- a/tests/package_name/SConscript
+++ b/tests/package_name/SConscript
@@ -22,7 +22,7 @@
 
     data = open(str(source[0]), 'r').read()
     
-    type_names = ['AllTypes', 'MyEnum', 'HugeEnum']
+    type_names = ['AllTypes', 'MyEnum', 'HugeEnum', 'NonZeroBasedEnum']
     for name in type_names:
         data = data.replace(name, 'test_package_' + name)
     
diff --git a/tests/package_name_nanopb/SConscript b/tests/package_name_nanopb/SConscript
index 990602d..9088f12 100644
--- a/tests/package_name_nanopb/SConscript
+++ b/tests/package_name_nanopb/SConscript
@@ -24,7 +24,7 @@
 
     data = open(str(source[0]), 'r').read()
     
-    type_names = ['AllTypes', 'MyEnum', 'HugeEnum']
+    type_names = ['AllTypes', 'MyEnum', 'HugeEnum', 'NonZeroBasedEnum']
     for name in type_names:
         data = data.replace(name, 'test_package_' + name)