diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3bcfcd9518..24d0a57f3ee 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## **[Unreleased]**
 
+- [#960](https://github.com/wasmerio/wasmer/pull/960) Fix `runtime-c-api` header files when compiled by clang.
 - [#925](https://github.com/wasmerio/wasmer/pull/925) Host functions can be closures with a captured environment.
 - [#917](https://github.com/wasmerio/wasmer/pull/917) Host functions (aka imported functions) may not have `&mut vm::Ctx` as first argument, i.e. the presence of the `&mut vm::Ctx` argument is optional.
 - [#915](https://github.com/wasmerio/wasmer/pull/915) All backends share the same definition of `Trampoline` (defined in `wasmer-runtime-core`).
diff --git a/lib/runtime-c-api/build.rs b/lib/runtime-c-api/build.rs
index 7c518398c63..7750b00813d 100644
--- a/lib/runtime-c-api/build.rs
+++ b/lib/runtime-c-api/build.rs
@@ -13,19 +13,21 @@ fn main() {
     out_wasmer_header_file.push("wasmer");
 
     const WASMER_PRE_HEADER: &str = r#"
-#ifndef WASMER_H_MACROS
+#if !defined(WASMER_H_MACROS)
 #define WASMER_H_MACROS
-#if MSVC
-#ifdef _M_AMD64
+
+#if defined(MSVC)
+#if defined(_M_AMD64)
 #define ARCH_X86_64
 #endif
 #endif
 
-#if GCC
-#ifdef __x86_64__
+#if defined(GCC) || defined(__clang__)
+#if defined(__x86_64__)
 #define ARCH_X86_64
 #endif
 #endif
+
 #endif // WASMER_H_MACROS
 "#;
     // Generate the C bindings in the `OUT_DIR`.
diff --git a/lib/runtime-c-api/wasmer.h b/lib/runtime-c-api/wasmer.h
index bc4a3ed4fe6..836a41df215 100644
--- a/lib/runtime-c-api/wasmer.h
+++ b/lib/runtime-c-api/wasmer.h
@@ -1,17 +1,19 @@
 
-#ifndef WASMER_H_MACROS
+#if !defined(WASMER_H_MACROS)
 #define WASMER_H_MACROS
-#if MSVC
-#ifdef _M_AMD64
+
+#if defined(MSVC)
+#if defined(_M_AMD64)
 #define ARCH_X86_64
 #endif
 #endif
 
-#if GCC
-#ifdef __x86_64__
+#if defined(GCC) || defined(__clang__)
+#if defined(__x86_64__)
 #define ARCH_X86_64
 #endif
 #endif
+
 #endif // WASMER_H_MACROS
 
 
diff --git a/lib/runtime-c-api/wasmer.hh b/lib/runtime-c-api/wasmer.hh
index acf4b20e797..79c350d6080 100644
--- a/lib/runtime-c-api/wasmer.hh
+++ b/lib/runtime-c-api/wasmer.hh
@@ -1,17 +1,19 @@
 
-#ifndef WASMER_H_MACROS
+#if !defined(WASMER_H_MACROS)
 #define WASMER_H_MACROS
-#if MSVC
-#ifdef _M_AMD64
+
+#if defined(MSVC)
+#if defined(_M_AMD64)
 #define ARCH_X86_64
 #endif
 #endif
 
-#if GCC
-#ifdef __x86_64__
+#if defined(GCC) || defined(__clang__)
+#if defined(__x86_64__)
 #define ARCH_X86_64
 #endif
 #endif
+
 #endif // WASMER_H_MACROS