diff --git a/panwrap/panwrap-decoder.c b/panwrap/panwrap-decoder.c
index 7f4ef38fc7c47861c7114c280d68af843917f438..04af0e141072269b757016503be92f010fa17bf4 100644
--- a/panwrap/panwrap-decoder.c
+++ b/panwrap/panwrap-decoder.c
@@ -15,6 +15,10 @@
 #include "panwrap.h"
 #include <mali-ioctl.h>
 #include <mali-job.h>
+#include <stdio.h>
+
+extern char* replace_fragment;
+extern char* replace_vertex;
 
 static char *panwrap_job_type_name(enum mali_job_type type)
 {
@@ -232,11 +236,28 @@ void panwrap_decode_vertex_or_tiler_job(const struct mali_job_descriptor_header
 	if (meta_ptr) {
 		meta = panwrap_fetch_gpu_mem(NULL, meta_ptr, sizeof(*meta));
 
+		/* For testing the shader compiler infrastructure, panloader
+		 * can replace shaders at runtime, configurable by
+		 * environmental variables. */
+
+		char *replacement = h->job_type == JOB_TYPE_VERTEX ?
+			replace_vertex : replace_fragment;
+
+		if (*replacement) {
+			/* TODO: Determine size and possibly allocate our own
+			 * shader buffer */
+
+			FILE *fp = fopen(replacement, "rb");
+			fread(meta->shader, 1, 64, fp);
+			fclose(fp);
+		}
+
 		panwrap_log("Shader blob: @ " MALI_PTR_FMT "\n", meta_ptr);
 		panwrap_indent++;
 		panwrap_log_hexdump(
 		    panwrap_fetch_gpu_mem(NULL, meta->shader, 832), 832);
 		panwrap_indent--;
+
 	} else
 		panwrap_log("<no shader>\n");
 
diff --git a/panwrap/panwrap-syscall.c b/panwrap/panwrap-syscall.c
index 0ab9c61f3500c7f5e530be36dcb9c3760e85f12a..55971b5a87b59f36121f699741cfc272dc43bc2d 100644
--- a/panwrap/panwrap-syscall.c
+++ b/panwrap/panwrap-syscall.c
@@ -111,9 +111,13 @@ static LIST_HEAD(mmaps);
 
 static bool step_mode;
 static long log_delay;
+char* replace_fragment;
+char* replace_vertex;
 PANLOADER_CONSTRUCTOR {
 	step_mode = panwrap_parse_env_bool("PANWRAP_STEP_MODE", false);
 	log_delay = panwrap_parse_env_long("PANWRAP_LOG_DELAY", 0);
+	replace_fragment = panwrap_parse_env_string("PANWRAP_REPLACE_FRAGMENT", "");
+	replace_vertex = panwrap_parse_env_string("PANWRAP_REPLACE_VERTEX", "");
 }
 
 #define LOCK()   pthread_mutex_lock(&l);
diff --git a/panwrap/panwrap-util.c b/panwrap/panwrap-util.c
index d1cdd953b25317c3999ad380a3c379c37de14a32..62b71bb4b7bc92915cc2e9e32330ade5d935b8d4 100644
--- a/panwrap/panwrap-util.c
+++ b/panwrap/panwrap-util.c
@@ -279,6 +279,18 @@ panwrap_parse_env_long(const char *env, long def)
 	return ret;
 }
 
+char *
+panwrap_parse_env_string(const char *env, char *def)
+{
+	const char *val = getenv(env);
+
+	if (!val)
+		return def;
+
+	return val;
+}
+
+
 PANLOADER_CONSTRUCTOR {
 	const char *env;
 
diff --git a/panwrap/panwrap.h b/panwrap/panwrap.h
index ff9b8e48e1edd7bda2dd9e0edcafd16bf5ffa70e..13190e73f51a0ee73211d9f586281f52c53dd038 100644
--- a/panwrap/panwrap.h
+++ b/panwrap/panwrap.h
@@ -47,6 +47,7 @@ void panwrap_log_hexdump_trimmed(const void *data, size_t size);
 
 bool panwrap_parse_env_bool(const char *env, bool def);
 long panwrap_parse_env_long(const char *env, long def);
+char * panwrap_parse_env_string(const char *env, char *def);
 
 extern short panwrap_indent;