diff --git a/scp.h b/scp.h
index 188486c8..039f8102 100644
--- a/scp.h
+++ b/scp.h
@@ -212,7 +212,7 @@ void sim_debug_bits (uint32 dbits, DEVICE* dptr, BITFIELD* bitdefs,
 void sim_debug (uint32 dbits, DEVICE* dptr, const char* fmt, ...) GCC_FMT_ATTR(3, 4);
 #else
 void _sim_debug (uint32 dbits, DEVICE* dptr, const char* fmt, ...) GCC_FMT_ATTR(3, 4);
-#define sim_debug(dbits, dptr, ...) if (sim_deb && dptr && ((dptr)->dctrl & dbits)) _sim_debug (dbits, dptr, __VA_ARGS__); else (void)0
+#define sim_debug(dbits, dptr, ...) do { if (sim_deb && dptr && ((dptr)->dctrl & dbits)) _sim_debug (dbits, dptr, __VA_ARGS__);} while (0)
 #endif
 void fprint_stopped_gen (FILE *st, t_stat v, REG *pc, DEVICE *dptr);
 #define SCP_HELP_FLAT   (1u << 31)       /* Force flat help when prompting is not possible */