diff --git a/contrib/pg_upgrade/check.c b/contrib/pg_upgrade/check.c
index d5d6bedb68e..453b0078996 100644
--- a/contrib/pg_upgrade/check.c
+++ b/contrib/pg_upgrade/check.c
@@ -19,6 +19,35 @@ static void check_for_isn_and_int8_passing_mismatch(migratorContext *ctx,
 static void check_for_reg_data_type_usage(migratorContext *ctx, Cluster whichCluster);
 
 
+/*
+ * fix_path_separator
+ * For non-Windows, just return the argument.
+ * For Windows convert any forward slash to a backslash
+ * such as is suitable for arguments to builtin commands 
+ * like RMDIR and DEL.
+ */
+static char *fix_path_separator(char *path)
+{
+#ifdef WIN32
+
+	char *result;
+	char *c;
+
+	result = pg_strdup(path);
+
+	for (c = result; *c != '\0'; c++)
+		if (*c == '/')
+			*c = '\\';
+
+	return result;
+
+#else
+
+	return path;
+
+#endif
+}
+
 void
 output_check_banner(migratorContext *ctx, bool *live_check)
 {
@@ -402,7 +431,7 @@ create_script_for_old_cluster_deletion(migratorContext *ctx,
 #endif
 
 	/* delete old cluster's default tablespace */
-	fprintf(script, RMDIR_CMD " %s\n", ctx->old.pgdata);
+	fprintf(script, RMDIR_CMD " %s\n", fix_path_separator(ctx->old.pgdata));
 
 	/* delete old cluster's alternate tablespaces */
 	for (tblnum = 0; tblnum < ctx->num_tablespaces; tblnum++)
@@ -419,14 +448,17 @@ create_script_for_old_cluster_deletion(migratorContext *ctx,
 			fprintf(script, "\n");
 			/* remove PG_VERSION? */
 			if (GET_MAJOR_VERSION(ctx->old.major_version) <= 804)
-				fprintf(script, RM_CMD " %s%s/PG_VERSION\n",
-						ctx->tablespaces[tblnum], ctx->old.tablespace_suffix);
+				fprintf(script, RM_CMD " %s%s%cPG_VERSION\n",
+						fix_path_separator(ctx->tablespaces[tblnum]),
+						fix_path_separator(ctx->old.tablespace_suffix),
+						PATH_SEPARATOR);
 
 			for (dbnum = 0; dbnum < ctx->new.dbarr.ndbs; dbnum++)
 			{
-				fprintf(script, RMDIR_CMD " %s%s/%d\n",
-						ctx->tablespaces[tblnum], ctx->old.tablespace_suffix,
-						ctx->old.dbarr.dbs[dbnum].db_oid);
+				fprintf(script, RMDIR_CMD " %s%s%c%d\n",
+						fix_path_separator(ctx->tablespaces[tblnum]),
+						fix_path_separator(ctx->old.tablespace_suffix),
+						PATH_SEPARATOR, ctx->old.dbarr.dbs[dbnum].db_oid);
 			}
 		}
 		else
@@ -436,7 +468,8 @@ create_script_for_old_cluster_deletion(migratorContext *ctx,
 			 * or a version-specific subdirectory.
 			 */
 			fprintf(script, RMDIR_CMD " %s%s\n",
-					ctx->tablespaces[tblnum], ctx->old.tablespace_suffix);
+					fix_path_separator(ctx->tablespaces[tblnum]),
+					fix_path_separator(ctx->old.tablespace_suffix));
 	}
 
 	fclose(script);
diff --git a/contrib/pg_upgrade/pg_upgrade.h b/contrib/pg_upgrade/pg_upgrade.h
index bfcabb390e0..3c3ca6daf6a 100644
--- a/contrib/pg_upgrade/pg_upgrade.h
+++ b/contrib/pg_upgrade/pg_upgrade.h
@@ -38,6 +38,7 @@
 #define pg_copy_file		copy_file
 #define pg_mv_file			rename
 #define pg_link_file		link
+#define PATH_SEPARATOR      '/'
 #define RM_CMD				"rm -f"
 #define RMDIR_CMD			"rm -rf"
 #define SHELL_EXT			"sh"
@@ -46,6 +47,7 @@
 #define pg_mv_file			pgrename
 #define pg_link_file		win32_pghardlink
 #define sleep(x)			Sleep(x * 1000)
+#define PATH_SEPARATOR      '\\'
 #define RM_CMD				"DEL /q"
 #define RMDIR_CMD			"RMDIR /s/q"
 #define SHELL_EXT			"bat"