diff --git a/rtl/openbsd/Makefile b/rtl/openbsd/Makefile
index 221a927d8d..fa82873850 100644
--- a/rtl/openbsd/Makefile
+++ b/rtl/openbsd/Makefile
@@ -364,6 +364,9 @@ 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 230f80a1cb..6293532e63 100644
--- a/rtl/openbsd/Makefile.fpc
+++ b/rtl/openbsd/Makefile.fpc
@@ -76,6 +76,11 @@ 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