diff --git a/src/runtime_lib.jl b/src/runtime_lib.jl
index 263c700..e5b4124 100644
--- a/src/runtime_lib.jl
+++ b/src/runtime_lib.jl
@@ -145,10 +145,10 @@ function write_bool(ptr, from_bits, value)
 
     segment = ptr.traverser.segments[ptr.segment]
     # println("Writing value ", value, " at segment ", ptr.segment, ", byte ", ptr.offset * 8 + from ÷ 8)
-    byte = unsafe_load!(Ptr{type}(pointer(segment) + 8 * ptr.offset + byte_position))
+    byte = unsafe_load(Ptr{UInt8}(pointer(segment) + 8 * ptr.offset + byte_position))
     # make the desired position zero and then place `value` to it
     byte = byte & ~(UInt8(1) << in_byte_position) | (value << in_byte_position)
-    unsafe_store!(Ptr{type}(pointer(segment) + 8 * ptr.offset + byte_position), byte)
+    unsafe_store!(Ptr{UInt8}(pointer(segment) + 8 * ptr.offset + byte_position), byte)
 end
 
 # "Bits" types except for bool.
diff --git a/src/schema.capnp.jl b/src/schema.capnp.jl
index ff079f5..1247654 100644
--- a/src/schema.capnp.jl
+++ b/src/schema.capnp.jl
@@ -1445,35 +1445,35 @@ if !@isdefined(capnp); eval(:(module capnp end)); end
             Capnp.write_bits(ptr, 0, UInt16, 1) # union discriminant
         end
         function Value_getInt8(ptr)
-            value = Capnp.read_bits(ptr, 2, UInt8)
+            value = Capnp.read_bits(ptr, 2, Int8)
             value
         end
         function Value_setInt8(ptr, value)
-            Capnp.write_bits(ptr, 2, UInt8, value)
+            Capnp.write_bits(ptr, 2, Int8, value)
             Capnp.write_bits(ptr, 0, UInt16, 2) # union discriminant
         end
         function Value_getInt16(ptr)
-            value = Capnp.read_bits(ptr, 2, UInt16)
+            value = Capnp.read_bits(ptr, 2, Int16)
             value
         end
         function Value_setInt16(ptr, value)
-            Capnp.write_bits(ptr, 2, UInt16, value)
+            Capnp.write_bits(ptr, 2, Int16, value)
             Capnp.write_bits(ptr, 0, UInt16, 3) # union discriminant
         end
         function Value_getInt32(ptr)
-            value = Capnp.read_bits(ptr, 4, UInt32)
+            value = Capnp.read_bits(ptr, 4, Int32)
             value
         end
         function Value_setInt32(ptr, value)
-            Capnp.write_bits(ptr, 4, UInt32, value)
+            Capnp.write_bits(ptr, 4, Int32, value)
             Capnp.write_bits(ptr, 0, UInt16, 4) # union discriminant
         end
         function Value_getInt64(ptr)
-            value = Capnp.read_bits(ptr, 8, UInt64)
+            value = Capnp.read_bits(ptr, 8, Int64)
             value
         end
         function Value_setInt64(ptr, value)
-            Capnp.write_bits(ptr, 8, UInt64, value)
+            Capnp.write_bits(ptr, 8, Int64, value)
             Capnp.write_bits(ptr, 0, UInt16, 5) # union discriminant
         end
         function Value_getUint8(ptr)
diff --git a/src/schema_tree.jl b/src/schema_tree.jl
index f1e5d39..a9f2a6c 100644
--- a/src/schema_tree.jl
+++ b/src/schema_tree.jl
@@ -92,10 +92,10 @@ capnp_sizeof(::SchemaFloat32) = 4
 capnp_sizeof(::SchemaFloat64) = 8
 
 # capnp_type_to_bits_type(::SchemaTypeBool) = Bool see capnp_sizeof
-capnp_type_to_bits_type(::SchemaInt8) = UInt8
-capnp_type_to_bits_type(::SchemaInt16) = UInt16
-capnp_type_to_bits_type(::SchemaInt32) = UInt32
-capnp_type_to_bits_type(::SchemaInt64) = UInt64
+capnp_type_to_bits_type(::SchemaInt8) = Int8
+capnp_type_to_bits_type(::SchemaInt16) = Int16
+capnp_type_to_bits_type(::SchemaInt32) = Int32
+capnp_type_to_bits_type(::SchemaInt64) = Int64
 capnp_type_to_bits_type(::SchemaUInt8) = UInt8
 capnp_type_to_bits_type(::SchemaUInt16) = UInt16
 capnp_type_to_bits_type(::SchemaUInt32) = UInt32
diff --git a/test/elementary.capnp b/test/elementary.capnp
new file mode 100644
index 0000000..dd8f74c
--- /dev/null
+++ b/test/elementary.capnp
@@ -0,0 +1,7 @@
+@0x930cadbc14628588;
+
+struct Test {
+    booleanFalse @0 :Bool;
+    booleanTrue @1 :Bool;
+    signed64 @2 :Int64;
+}
\ No newline at end of file
diff --git a/test/runtests.jl b/test/runtests.jl
index 2eeeabd..e3317ae 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -27,6 +27,36 @@ end
     @test result == expected
 end
 
+@testset "Elementary types" begin
+    run(`capnpc -o./capnpc-jl test/elementary.capnp`)
+    include("elementary.capnp.jl")
+
+    # writing part
+    message = Capnp.AllocMessageBuilder()
+    test = initRoot_Test(message)
+    Test_setBooleanFalse(test, false)
+    Test_setBooleanTrue(test, true)
+    Test_setSigned64(test, -1)
+
+    # finish writing and flush into buffer for reading
+    buffer = IOBuffer()
+    writeMessageToStream(message, buffer)
+    seek(buffer, 0)
+
+    # reading part
+    message = Capnp.MessageReader(buffer)
+    test = root_Test(message)
+
+    booleanFalse = Test_getBooleanFalse(test)
+    @test booleanFalse == false
+
+    booleanTrue = Test_getBooleanTrue(test)
+    @test booleanTrue == true
+
+    signed64 = Test_getSigned64(test)
+    @test signed64 == -1
+end
+
 @testset "Lists" begin
     run(`capnpc -o./capnpc-jl test/lists.capnp`)
     include("lists.capnp.jl")