diff --git a/Changes b/Changes
index 877a19082..4e3e5a0c5 100644
--- a/Changes
+++ b/Changes
@@ -15,6 +15,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 **** Fix multiple .v files being read in random order. [Stefan Thiede]
 
+**** Fix internal error when params get non-constants. [Johan Wouters]
+
 * Verilator 3.661 2008/04/04
 
 ***  The --enable-defenv configure option added in 3.660 is now the default.
diff --git a/src/V3Param.cpp b/src/V3Param.cpp
index 471977631..3ebe929d6 100644
--- a/src/V3Param.cpp
+++ b/src/V3Param.cpp
@@ -254,6 +254,7 @@ void ParamVisitor::visit(AstCell* nodep, AstNUser*) {
 		if (!constp) {
 		    //if (debug()) pinp->dumpTree(cout,"error:");
 		    pinp->v3error("Can't convert defparam value to constant: Param "<<pinp->name()<<" of "<<nodep->prettyName());
+		    pinp->exprp()->replaceWith(new AstConst(pinp->fileline(), V3Number(pinp->fileline(), pinp->width(), 0)));
 		} else {
 		    longname += "_" + paramSmallName(nodep->modp(),pinp->modVarp())+constp->num().ascii(false);
 		}