diff --git a/fco2/fco_support.h b/fco2/fco_support.h
new file mode 100644
index 0000000..6a9aaf8
--- /dev/null
+++ b/fco2/fco_support.h
@@ -0,0 +1,53 @@
+/* C99 support definitions for FCO. */
+
+#ifndef FCO_SUPPORT_H
+#define FCO_SUPPORT_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <float.h>
+
+#define occam_mostneg_bool false
+#define occam_mostpos_bool true
+#define occam_mostneg_char CHAR_MIN
+#define occam_mostpos_char CHAR_MAX
+#define occam_mostneg_int INT_MIN
+#define occam_mostpos_int INT_MAX
+#define occam_mostneg_int16_t INT16_MIN
+#define occam_mostpos_int16_t INT16_MAX
+#define occam_mostneg_int32_t INT32_MIN
+#define occam_mostpos_int32_t INT32_MAX
+#define occam_mostneg_int64_t INT64_MIN
+#define occam_mostpos_int64_t INT64_MAX
+#define occam_mostneg_float -FLT_MAX
+#define occam_mostpos_float FLT_MAX
+#define occam_mostneg_double -DBL_MAX
+#define occam_mostpos_double DBL_MAX
+
+/* FIXME All of these need to check for overflow and report errors appropriately. */
+static int occam_add(int a, int b) {
+	return a + b;
+}
+static int occam_subtr(int a, int b) {
+	return a - b;
+}
+static int occam_mul(int a, int b) {
+	return a * b;
+}
+static int occam_div(int a, int b) {
+	if (b == 0) {
+		SetErr ();
+	}
+	return a / b;
+}
+static int occam_rem(int a, int b) {
+	if (b == 0) {
+		SetErr ();
+	}
+	return a % b;
+}
+static bool occam_after(int a, int b) {
+	return (a - b) > 0;
+}
+
+#endif