diff --git a/bin/verilator b/bin/verilator
index ccdbc8f17..bbb85027b 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -926,9 +926,10 @@ Backward compatible alias for "--pins-bv 65".  Note that's a 65, not a 64.
 
 Specifies SystemC inputs/outputs of greater than or equal to I<width> bits
 wide should use sc_bv's instead of uint32/vluint64_t's.  The default is
-"--pins-bv 65".  Versions before Verilator 3.671 defaulted to "--pins-bv
-33".  The more sc_bv is used, the worse for performance.  Use the
-"/*verilator sc_bv*/" attribute to select specific ports to be sc_bv.
+"--pins-bv 65", and the value must be less than or equal to 65.  Versions
+before Verilator 3.671 defaulted to "--pins-bv 33".  The more sc_bv is
+used, the worse for performance.  Use the "/*verilator sc_bv*/" attribute
+to select specific ports to be sc_bv.
 
 =item --pins-sc-uint
 
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index fa30d16a6..04f9c6898 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -986,6 +986,7 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
 	    }
 	    else if ( !strcmp (sw, "-pins-bv") && (i+1)<argc ) {
 		shift; m_pinsBv = atoi(argv[i]);
+		if (m_pinsBv > 65) fl->v3fatal("--pins-bv maximum is 65: "<<argv[i]);
 	    }
 	    else if ( !strcmp (sw, "-pipe-filter") && (i+1)<argc ) {
 		shift; m_pipeFilter = argv[i];