diff --git a/rtl/openbsd/Makefile b/rtl/openbsd/Makefile
index 4db01ae9dd..47de6ca852 100644
--- a/rtl/openbsd/Makefile
+++ b/rtl/openbsd/Makefile
@@ -346,6 +346,9 @@ PRT0=prt0
 ifdef RELEASE
 override FPCOPT+=-Ur
 endif
+ifeq ($(FPC_USE_SYSCALL),)
+override FPCOPT+=-dFPC_USE_LIBC
+endif
 CPU_UNITS=
 SYSINIT_UNITS=si_prc si_c si_dll si_g
 LOADERS=prt0
diff --git a/rtl/openbsd/Makefile.fpc b/rtl/openbsd/Makefile.fpc
index dc8aeb11d8..b7f6fcf994 100644
--- a/rtl/openbsd/Makefile.fpc
+++ b/rtl/openbsd/Makefile.fpc
@@ -75,6 +75,11 @@ ifdef RELEASE
 override FPCOPT+=-Ur
 endif
 
+# OpenBSD defaults to libc, no syscalls
+ifeq ($(FPC_USE_SYSCALL),)
+override FPCOPT+=-dFPC_USE_LIBC
+endif
+
 CPU_UNITS=
 SYSINIT_UNITS=si_prc si_c si_dll si_g