diff --git a/src/ops.c b/src/ops.c
new file mode 100644
index 0000000..8884e64
--- /dev/null
+++ b/src/ops.c
@@ -0,0 +1,41 @@
+#include "config.h"
+#include "types.h"
+#include "ops.h"
+
+/*
+  Variable VM instruction operand sizes, must be consistent with ops_t enumeration (ops.h)
+*/
+
+const index_t ops_s[] = {
+  0,
+  // ADD=1,      DIV,          MUL,        SUB,        NEG,        MOD,
+  0,          0,            0,          0,          0,          0,
+  // AND,        OR,           NOT,
+  0,          0,            0,
+  // EQ,         NEQ,          LT,         GT,         LE,         GE,       CMPS,
+  0,          0,            0,          0,          0,          0,        0,
+  // DROPD,      DROPF,
+  index_s,    index_s,
+  // PUSHD,      PUSHF,        NTHD,       NTHF,    TOF,        SETF,       SETSP,      INCSP,
+  number_s,   number_s,     index_s,    index_s,    index_s,    index_s,    index_s,    index_s,
+  // INCHAR,     INNUMBER,     INSTRING,   INARRAY,
+  0,        0,              0,          0,
+  // OUTCHAR,    OUTNUMBER,    OUTSTRING,  OUTARRY,
+  0,        0,              0,          0,
+  // STRING
+  index_s,
+  // JMP      JZ,           JNZ,          TESTRANGE,  LOOP,
+  address_s,  address_s,    address_s,    2*index_s,  0,
+  // READ,       WRITE,        READS,      WRITES,     DATA,      EVENT,      ERR,        EMIT,
+  address_s,  address_s,    address_s,    address_s,  index_s,    address_s,  address_s,  index_s,
+  // INTERRUPT,   RESUME,   CALL,         CCALL,      PROC,       FUNC,       RETURN,     FORK,   YIELD
+  index_s,        index_s,  address_s,    index_s,    index_s,    index_s,    index_s,    0,      0,
+#if HAS_LOCK > 0
+  // LOCK,    UNLOCK
+  address_s,  address_s,
+#endif
+  // END,    ENV
+  0,         index_s
+};
+
+