diff --git a/library/constant_time.c b/library/constant_time.c
index 5e1a577..2faba69 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -81,7 +81,7 @@
 #if defined(__arm__) || defined(__thumb__) || defined(__thumb2__)
     asm volatile ("ldr %0, [%1]" : "=r" (r) : "r" (p) :);
 #elif defined(__aarch64__)
-    asm volatile ("ldr %w0, [%1]" : "=r" (r) : MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT (p) :);
+    asm volatile ("ldr %w0, [%1]" : "=r" (r) : MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT(p) :);
 #endif
     return r;
 }