diff -urpN busybox-1.15.2/editors/awk.c busybox-1.15.2-awk/editors/awk.c
--- busybox-1.15.2/editors/awk.c	2009-10-08 02:59:09.000000000 +0200
+++ busybox-1.15.2-awk/editors/awk.c	2009-11-30 02:05:12.000000000 +0100
@@ -2393,12 +2393,14 @@ static var *evaluate(node *op, var *res)
 
 		case XC( OC_MOVE ):
 			/* if source is a temporary string, jusk relink it to dest */
-			if (R.v == v1+1 && R.v->string) {
-				res = setvar_p(L.v, R.v->string);
-				R.v->string = NULL;
-			} else {
+//Disabled: if R.v is numeric but happens to have cached R.v->string,
+//then L.v ends up being a string, which is wrong
+//			if (R.v == v1+1 && R.v->string) {
+//				res = setvar_p(L.v, R.v->string);
+//				R.v->string = NULL;
+//			} else {
 				res = copyvar(L.v, R.v);
-			}
+//			}
 			break;
 
 		case XC( OC_TERNARY ):
diff -urpN busybox-1.15.2/testsuite/awk.tests busybox-1.15.2-awk/testsuite/awk.tests
--- busybox-1.15.2/testsuite/awk.tests	2009-09-26 15:14:57.000000000 +0200
+++ busybox-1.15.2-awk/testsuite/awk.tests	2009-11-30 02:05:12.000000000 +0100
@@ -47,4 +47,21 @@ testing "awk NF in BEGIN" \
 	":0::::\n" \
 	"" ""
 
+prg='
+function b(tmp) {
+	tmp = 0;
+	print "" tmp; #this line causes the bug
+	return tmp;
+}
+function c(tmpc) {
+	tmpc = b(); return tmpc;
+}
+BEGIN {
+	print (c() ? "string" : "number");
+}'
+testing "awk string cast (bug 725)" \
+	"awk '$prg'" \
+	"0\nnumber\n" \
+	"" ""
+
 exit $FAILCOUNT