diff --git a/context/cocore.c b/context/cocore.c
index bc78452..570f87b 100644
--- a/context/cocore.c
+++ b/context/cocore.c
@@ -33,7 +33,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
-#if !defined(__APPLE__)
+#if !(defined(__APPLE__) || defined(__OpenBSD__))
 #include <malloc.h>
 #endif
 #include <assert.h>
diff --git a/context/platform.h b/context/platform.h
index dae7822..04ddbc3 100644
--- a/context/platform.h
+++ b/context/platform.h
@@ -62,6 +62,14 @@
 #define MALLOC_ALIGNED(alignment, size) valloc(size)
 #define FREE_ALIGNED(mem)               free(mem)
 
+#elif defined(__OpenBSD__)
+/* OpenBSD stack memory has to be specially allocated with mmap() */
+#define MALLOC_ALIGNED(alignment, size) \
+    mmap(NULL, size, PROT_READ | PROT_WRITE, \
+        MAP_ANONYMOUS | MAP_PRIVATE | MAP_STACK, -1, 0)
+#define FREE_ALIGNED(mem)               ((void) 0)
+/* XXX will leak memory; maybe won't crash with short-lived processes */
+
 #elif defined(WIN32)
 /* This is what we have to use on 32-bit Windows. */
 #define MALLOC_ALIGNED(alignment, size) \