diff --git a/betterproto/__init__.py b/betterproto/__init__.py
index fc178b5..ee36708 100644
--- a/betterproto/__init__.py
+++ b/betterproto/__init__.py
@@ -595,6 +595,9 @@ class Message(ABC):
             elif meta.proto_type in [TYPE_SINT32, TYPE_SINT64]:
                 # Undo zig-zag encoding
                 value = (value >> 1) ^ (-(value & 1))
+            elif meta.proto_type == TYPE_BOOL:
+                # Booleans use a varint encoding, so convert it to true/false.
+                value = value > 0
         elif wire_type in [WIRE_FIXED_32, WIRE_FIXED_64]:
             fmt = _pack_fmt(meta.proto_type)
             value = struct.unpack(fmt, value)[0]
diff --git a/betterproto/tests/bool.json b/betterproto/tests/bool.json
new file mode 100644
index 0000000..348e031
--- /dev/null
+++ b/betterproto/tests/bool.json
@@ -0,0 +1,3 @@
+{
+  "value": true
+}
diff --git a/betterproto/tests/bool.proto b/betterproto/tests/bool.proto
new file mode 100644
index 0000000..237e7db
--- /dev/null
+++ b/betterproto/tests/bool.proto
@@ -0,0 +1,5 @@
+syntax = "proto3";
+
+message Test {
+    bool value = 1;
+}