diff --git a/historic/jam/src/jam.h b/historic/jam/src/jam.h
index bddb92db1..3851822c5 100644
--- a/historic/jam/src/jam.h
+++ b/historic/jam/src/jam.h
@@ -359,6 +359,11 @@
 # define OSMINOR "OS=UNIXWARE"
 # define OS_UNIXWARE
 # endif
+# ifdef __OpenBSD__
+# define OSMINOR "OS=OPENBSD"
+# define OS_OPENBSD
+# define unix
+# endif
 # ifndef OSMINOR
 # define OSMINOR "OS=UNKNOWN"
 # endif
@@ -393,7 +398,8 @@
      !defined(OS_MACHTEN) && \
      !defined(OS_MACOSX) && \
      !defined(OS_RHAPSODY) && \
-     !defined(OS_MVS)
+     !defined(OS_MVS) && \
+     !defined(OS_OPENBSD)
 # include <malloc.h>
 # endif
 
diff --git a/jam_src/jam.h b/jam_src/jam.h
index bddb92db1..3851822c5 100644
--- a/jam_src/jam.h
+++ b/jam_src/jam.h
@@ -359,6 +359,11 @@
 # define OSMINOR "OS=UNIXWARE"
 # define OS_UNIXWARE
 # endif
+# ifdef __OpenBSD__
+# define OSMINOR "OS=OPENBSD"
+# define OS_OPENBSD
+# define unix
+# endif
 # ifndef OSMINOR
 # define OSMINOR "OS=UNKNOWN"
 # endif
@@ -393,7 +398,8 @@
      !defined(OS_MACHTEN) && \
      !defined(OS_MACOSX) && \
      !defined(OS_RHAPSODY) && \
-     !defined(OS_MVS)
+     !defined(OS_MVS) && \
+     !defined(OS_OPENBSD)
 # include <malloc.h>
 # endif