diff --git a/lib/capn-malloc.c b/lib/capn-malloc.c
index 708294e..65fcb9f 100644
--- a/lib/capn-malloc.c
+++ b/lib/capn-malloc.c
@@ -8,6 +8,10 @@
  * of the MIT license.  See the LICENSE file for details.
  */
 
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#endif
+
 #include "capnp_c.h"
 #include "capnp_priv.h"
 #include <stdlib.h>
@@ -25,10 +29,6 @@ struct check_segment_alignment {
 };
 
 static struct capn_segment *create(void *u, uint32_t id, int sz) {
-	// Silence warnings about unused parameters.
-	UNUSED(u);
-	UNUSED(id);
-
 	struct capn_segment *s;
 	sz += sizeof(*s);
 	if (sz < 4096) {
diff --git a/lib/capn.c b/lib/capn.c
index 0677452..f9d22d8 100644
--- a/lib/capn.c
+++ b/lib/capn.c
@@ -7,7 +7,9 @@
  * of the MIT license.  See the LICENSE file for details.
  */
 
+#ifdef __GNUC__
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
 
 #include "capnp_c.h"
 
diff --git a/lib/capnp_c.h b/lib/capnp_c.h
index 58867a3..edbc43e 100644
--- a/lib/capnp_c.h
+++ b/lib/capnp_c.h
@@ -13,11 +13,7 @@
 
 #include <stdint.h>
 #include <stdio.h>
-
-// ssize_t is defined in unistd.h in GCC.
-#ifdef __GNUC__
 #include <unistd.h>
-#endif
 
 #if defined(unix) && !defined(__APPLE__)
 #include <endian.h>
@@ -33,7 +29,7 @@ typedef intmax_t ssize_t;
 #define UNUSED(x) (void)(x)
 #endif
 
-// Cross-platform macro ALIGNED_(x) aligns a struct by `x` bits.
+// Cross-platform macro ALIGNED_(x) aligns a struct by `x` bytes.
 #ifdef _MSC_VER
 #define ALIGNED_(x) __declspec(align(x))
 #endif