diff --git a/include/nsc.h b/include/nsc.h
index 4a7f7251..91519206 100644
--- a/include/nsc.h
+++ b/include/nsc.h
@@ -275,6 +275,7 @@ extern int nstr_coerce_val(struct valstr *, nsc_type, char *);
 extern int nstr_exec(struct nscstr *, int, void *);
 /* src/lib/common/nstreval.c */
 extern void nstr_exec_val(struct valstr *, natid, void *, nsc_type);
+extern int nstr_promote(int);
 extern char *symbol_by_value(int, struct symbol *);
 /* src/lib/global/nsc.c */
 extern void nsc_init(void);
diff --git a/src/lib/common/nstreval.c b/src/lib/common/nstreval.c
index 9bb35dc8..c730ff5a 100644
--- a/src/lib/common/nstreval.c
+++ b/src/lib/common/nstreval.c
@@ -160,6 +160,44 @@ nstr_exec_val(struct valstr *val, natid cnum, void *ptr, nsc_type want)
     val->val_type = valtype;
 }
 
+/*
+ * Promote VALTYPE.
+ * If VALTYPE is an integer type, return NSC_LONG.
+ * If VALTYPE is a floating-point type, return NSC_DOUBLE.
+ * If VALTYPE is a string type, return NSC_STRING.
+ */
+int
+nstr_promote(int valtype)
+{
+    switch (valtype) {
+    case NSC_LONG:
+    case NSC_DOUBLE:
+    case NSC_STRING:
+	break;
+    case NSC_CHAR:
+    case NSC_UCHAR:
+    case NSC_SHORT:
+    case NSC_USHORT:
+    case NSC_INT:
+    case NSC_XCOORD:
+    case NSC_YCOORD:
+    case NSC_HIDDEN:
+    case NSC_TIME:
+	valtype = NSC_LONG;
+	break;
+    case NSC_FLOAT:
+	valtype = NSC_DOUBLE;
+	break;
+    case NSC_STRINGY:
+	valtype = NSC_STRING;
+	break;
+    default:
+	CANT_REACH();
+	valtype = NSC_NOTYPE;
+    }
+    return valtype;
+}
+
 char *
 symbol_by_value(int key, struct symbol *table)
 {
diff --git a/src/lib/subs/nstr.c b/src/lib/subs/nstr.c
index 2ce08403..0142257c 100644
--- a/src/lib/subs/nstr.c
+++ b/src/lib/subs/nstr.c
@@ -49,8 +49,6 @@ static int nstr_string_ok(struct castr *ca, int idx);
 static struct valstr *nstr_resolve_sel(struct valstr *, struct castr *);
 static struct valstr *nstr_mkselval(struct valstr *, int, struct castr *);
 static struct valstr *nstr_resolve_id(struct valstr *, struct castr *, int, int);
-static int nstr_promote(int);
-
 
 /*
  * Compile conditions into array NP[LEN].
@@ -474,45 +472,6 @@ nstr_comp_val(char *str, struct valstr *val, int type)
     return tail;
 }
 
-
-/*
- * Promote VALTYPE.
- * If VALTYPE is an integer type, return NSC_LONG.
- * If VALTYPE is a floating-point type, return NSC_DOUBLE.
- * If VALTYPE is a string type, return NSC_STRING.
- */
-static int
-nstr_promote(int valtype)
-{
-    switch (valtype) {
-    case NSC_LONG:
-    case NSC_DOUBLE:
-    case NSC_STRING:
-	break;
-    case NSC_CHAR:
-    case NSC_UCHAR:
-    case NSC_SHORT:
-    case NSC_USHORT:
-    case NSC_INT:
-    case NSC_XCOORD:
-    case NSC_YCOORD:
-    case NSC_HIDDEN:
-    case NSC_TIME:
-	valtype = NSC_LONG;
-	break;
-    case NSC_FLOAT:
-	valtype = NSC_DOUBLE;
-	break;
-    case NSC_STRINGY:
-	valtype = NSC_STRING;
-	break;
-    default:
-	CANT_REACH();
-	valtype = NSC_NOTYPE;
-    }
-    return valtype;
-}
-
 static int
 cond_type_mismatch(char *str)
 {