diff --git a/driver/main.c b/driver/main.c
index c61a5cf4e..bda9da0e9 100644
--- a/driver/main.c
+++ b/driver/main.c
@@ -1403,10 +1403,20 @@ int main(int argc, char **argv)
 	/* Write values to the iconfig file. */
       fprintf(iconfig_file, "basedir:%s\n", base);
 
-	/* Tell the core where to find the system VPI modules. */
-      fprintf(iconfig_file, "module:%s%csystem.vpi\n", vpi_dir, sep);
-      fprintf(iconfig_file, "module:%s%cvhdl_sys.vpi\n", vpi_dir, sep);
-      fprintf(iconfig_file, "module:%s%cvhdl_textio.vpi\n", vpi_dir, sep);
+      char module_prefix[1024];
+      const char *module_suffix;
+      if (strcmp(vpi_dir, base) != 0) {
+	    snprintf(module_prefix, sizeof(module_prefix), "module:%s%c", vpi_dir, sep);
+	    module_suffix = ".vpi";
+      } else {
+	    snprintf(module_prefix, sizeof(module_prefix), "module:");
+	    module_suffix = "";
+      }
+
+	/* Tell the core where to find the built-in VPI modules. */
+      fprintf(iconfig_file, "%ssystem%s\n", module_prefix, module_suffix);
+      fprintf(iconfig_file, "%svhdl_sys%s\n", module_prefix, module_suffix);
+      fprintf(iconfig_file, "%svhdl_textio%s\n", module_prefix, module_suffix);
 
 	/* If verilog-2005/09/12/17/23 is enabled or icarus-misc or verilog-ams,
 	 * then include the v2005_math library. */
@@ -1417,13 +1427,13 @@ int main(int argc, char **argv)
           strcmp(generation, "2023") == 0 ||
           strcmp(gen_icarus, "icarus-misc") == 0 ||
           strcmp(gen_verilog_ams, "verilog-ams") == 0) {
-	    fprintf(iconfig_file, "module:%s%cv2005_math.vpi\n", vpi_dir, sep);
+	    fprintf(iconfig_file, "%sv2005_math%s\n", module_prefix, module_suffix);
       }
 	/* If verilog-ams or icarus_misc is enabled, then include the
 	 * va_math module as well. */
       if (strcmp(gen_verilog_ams,"verilog-ams") == 0 ||
           strcmp(gen_icarus, "icarus-misc") == 0) {
-	    fprintf(iconfig_file, "module:%s%cva_math.vpi\n", vpi_dir, sep);
+	    fprintf(iconfig_file, "%sva_math%s\n", module_prefix, module_suffix);
       }
       /* If verilog-2009 (SystemVerilog) is enabled, then include the
          v2009 module. */
@@ -1432,7 +1442,7 @@ int main(int argc, char **argv)
           strcmp(generation, "2012") == 0 ||
           strcmp(generation, "2017") == 0 ||
           strcmp(generation, "2023") == 0) {
-	    fprintf(iconfig_file, "module:%s%cv2009.vpi\n", vpi_dir, sep);
+	    fprintf(iconfig_file, "%sv2009%s\n", module_prefix, module_suffix);
       }
 
       if (mtm != 0) fprintf(iconfig_file, "-T:%s\n", mtm);