diff --git a/GNUmakefile b/GNUmakefile
index 0db02e7..49bda2b 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -1,11 +1,16 @@
 .PHONY: veryclean clean force export help test run
 
-F:= ifort
+F := ifort
 BUILD_DIR := build
 
 HP_LIB := $(BUILD_DIR)/libhp.a
 
+# Untested NAG support
+ifeq ($(F),nagfor)
+F_OPTS := -fpic -I $(BUILD_DIR)
+else
 F_OPTS := -fpic -module $(BUILD_DIR)
+endif
 
 ifdef debug
 F_OPTS += -ggdb -debug-parameters used