diff --git a/build.gradle b/build.gradle
index 1dfe2d877..dfa63748e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -20,7 +20,6 @@ buildscript {
     repositories {
         maven { url = 'https://files.minecraftforge.net/maven' }
         maven { url = 'https://repo.spongepowered.org/maven' }
-        jcenter()
         mavenCentral()
     }
     dependencies {
@@ -40,9 +39,15 @@ apply plugin: 'net.minecraftforge.gradle'
 apply plugin: 'org.spongepowered.mixin'
 apply plugin: "eclipse"
 
+// All jar files from this folder will be added automatically as runtime mod dependencies
+def extraModsDir = "extra-mods-${minecraft_version}"
+
 repositories {
+    flatDir {
+        name "extra-mods"
+        dir file(extraModsDir)
+    }
     mavenLocal()
-    jcenter()
     mavenCentral()
     maven { // modmaven, maven proxy
         name 'modmaven'
@@ -61,6 +66,16 @@ dependencies {
     runtimeOnly fg.deobf("mezz.jei:jei-${jei_minecraft_version}:${jei_version}")
     runtimeOnly fg.deobf("mcjty.theoneprobe:TheOneProbe-${minecraft_release}:${minecraft_release}-${top_version}")
 
+    // Locally sourced extra mods for runtime (i.e. testing)
+    for (extraModJar in fileTree(dir: extraModsDir, include: '*.jar')) {
+        def basename = extraModJar.name.substring(0, extraModJar.name.length() - ".jar".length())
+        def versionSep = basename.lastIndexOf('-')
+        assert versionSep != -1
+        def artifactId = basename.substring(0, versionSep)
+        def version = basename.substring(versionSep + 1)
+        runtimeOnly fg.deobf("extra-mods:$artifactId:$version")
+    }
+
     // unit test dependencies
     testCompile "junit:junit:4.13"
     
diff --git a/gradle.properties b/gradle.properties
index c88eb87cb..8d3587809 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -11,7 +11,7 @@ artifact_basename=appliedenergistics2
 minecraft_release=1.16
 minecraft_version=1.16.3
 mcp_mappings=20200916-1.16.2
-forge_version=34.0.8
+forge_version=34.1.15
 
 #########################################################
 # Provided APIs                                         #