diff --git a/build.gradle b/build.gradle
index 89a7b24..7fb722b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -40,6 +40,7 @@ dependencies {
     implementation('net.minecraft:launchwrapper:1.12') { transitive = false }
     implementation 'org.ow2.asm:asm:6.2'
     implementation 'org.ow2.asm:asm-commons:6.2'
+    compile 'com.vdurmont:semver4j:2.2.0'
 }
 
 minecraft {
diff --git a/src/main/java/org/dimdev/riftloader/Dependency.java b/src/main/java/org/dimdev/riftloader/Dependency.java
new file mode 100644
index 0000000..43349f5
--- /dev/null
+++ b/src/main/java/org/dimdev/riftloader/Dependency.java
@@ -0,0 +1,11 @@
+package org.dimdev.riftloader;
+
+public class Dependency {
+
+    public String id;
+    public String type;
+    public String load;
+    public String mavenId;
+    public String minVersion;
+    public String maxVersion;
+}
diff --git a/src/main/java/org/dimdev/riftloader/MissingDependencyException.java b/src/main/java/org/dimdev/riftloader/MissingDependencyException.java
new file mode 100644
index 0000000..1fdafe5
--- /dev/null
+++ b/src/main/java/org/dimdev/riftloader/MissingDependencyException.java
@@ -0,0 +1,7 @@
+package org.dimdev.riftloader;
+
+public class MissingDependencyException extends RuntimeException {
+    public MissingDependencyException(String s) {
+        super(s);
+    }
+}
diff --git a/src/main/java/org/dimdev/riftloader/ModInfo.java b/src/main/java/org/dimdev/riftloader/ModInfo.java
index 07e341f..d64c845 100644
--- a/src/main/java/org/dimdev/riftloader/ModInfo.java
+++ b/src/main/java/org/dimdev/riftloader/ModInfo.java
@@ -9,6 +9,8 @@ public class ModInfo {
 
     public String id;
     public String name;
+    public String version;
+    public List<Dependency> dependencies = new ArrayList<>();
     public List<String> authors = new ArrayList<>();
     public List<String> listeners = new ArrayList<>();
 }
diff --git a/src/main/java/org/dimdev/riftloader/RiftLoader.java b/src/main/java/org/dimdev/riftloader/RiftLoader.java
index 07e3929..19dcd7b 100644
--- a/src/main/java/org/dimdev/riftloader/RiftLoader.java
+++ b/src/main/java/org/dimdev/riftloader/RiftLoader.java
@@ -2,6 +2,8 @@
 
 import com.google.gson.Gson;
 import com.google.gson.JsonParseException;
+import com.vdurmont.semver4j.Semver;
+import com.vdurmont.semver4j.SemverException;
 import net.minecraft.launchwrapper.Launch;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -76,6 +78,7 @@ public void findMods(File modsDir) {
                     mod.source = file;
                     mod.id = "optifine";
                     mod.name = "Optifine";
+                    mod.version = "1.13-alpha8";
                     mod.authors.add("sp614x");
                     mod.listeners.add("org.dimdev.riftloader.OptifineLoader");
                     modInfoMap.put("optifine", mod);
@@ -136,6 +139,18 @@ private void loadModFromJson(InputStream in, File source) {
                 throw new ModConflictException("Duplicate mod '" + modInfo.id + "': " + modInfoMap.get(modInfo.id).source + ", " + modInfo.source);
             }
 
+            // Make sure the version is proper SemVer
+            if (modInfo.version == null) {
+                log.warn("Mod file " + modInfo.source + "'s riftmod.json is missing a 'version' field. This may affect dependencies!");
+            } else {
+                try {
+                    Semver version = new Semver(modInfo.version, Semver.SemverType.LOOSE);
+                } catch (SemverException t) {
+                    log.warn("Mod file " + modInfo.source + "'s riftmod.json has a malformed 'version' field. This may affect dependencies!");
+                    log.warn("SemVer error: " + t.getMessage());
+                }
+            }
+
             // Add the mod to the 'id -> mod info' map
             modInfoMap.put(modInfo.id, modInfo);
             log.info("Loaded mod '" + modInfo.id + "'");
@@ -150,6 +165,44 @@ public void sortMods() {
 
     public void initMods() {
         log.info("Initializing mods");
+
+        // Check dependencies
+        for (ModInfo modInfo : modInfoMap.values()) {
+            if (!modInfo.dependencies.isEmpty()) {
+                log.info("Found dependency list for " + modInfo.id);
+                for (Dependency dependency : modInfo.dependencies) {
+                    log.info(dependency.id);
+                    log.info(dependency.minVersion);
+                    log.info(dependency.load);
+                    if (!modInfoMap.containsKey(dependency.id)) {
+                        if (dependency.type.equals("hard")) throw new MissingDependencyException("Mod " + modInfo.source + " is missing hard dependency " + dependency.id + ":" + dependency.minVersion);
+                        else log.error("Mod " + modInfo.source + " is missing soft dependency " + dependency.id + ":" + dependency.minVersion + ". This may impact gameplay!");
+                    }
+                    ModInfo depInfo = modInfoMap.get(dependency.id);
+                    Semver trueVersion = new Semver(depInfo.version, Semver.SemverType.LOOSE);
+                    try {
+                        Semver lowestVersion = new Semver(dependency.minVersion, Semver.SemverType.LOOSE);
+                        if (trueVersion.isLowerThan(lowestVersion)) {
+                            if (dependency.type.equals("hard")) throw new MissingDependencyException("Mod " + modInfo.source + " has outdated hard dependency: " + dependency.id + " must be at least " + lowestVersion);
+                            else log.error("Mod " + modInfo.source + " has outdated soft dependency: " + dependency.id + " must be at least " + lowestVersion);
+                        }
+
+                        if (dependency.maxVersion != null) {
+                            Semver highestVersion = new Semver(dependency.maxVersion, Semver.SemverType.LOOSE);
+                            if (trueVersion.isGreaterThan(highestVersion)) {
+                                if (dependency.type.equals("hard")) throw new MissingDependencyException("Mod " + modInfo.source + " has outdated hard dependency: " + dependency.id + " must be at most " + highestVersion);
+                                else log.error("Mod " + modInfo.source + " has outdated soft dependency: " + dependency.id + " must be at most " + highestVersion);                            }
+                        }
+                    } catch (SemverException t) {
+                        if (dependency.type.equals("hard")) throw new MissingDependencyException("Mod " + modInfo.source + " has malformed hard dependency in " + dependency.id + ": SemVer error " + t.getMessage());
+                        else log.error("Mod " + modInfo.source + " has malformed soft dependency in " + dependency.id + ": SemVer error " + t.getMessage());
+                    }
+                }
+            } else {
+                log.info("Found no dependencies for " + modInfo.id);
+            }
+        }
+
         // Load all the mod jars
         for (ModInfo modInfo : modInfoMap.values()) {
             try {
diff --git a/src/main/resources/riftmod.json b/src/main/resources/riftmod.json
index 192688c..7e689fe 100644
--- a/src/main/resources/riftmod.json
+++ b/src/main/resources/riftmod.json
@@ -1,6 +1,7 @@
 {
   "id": "rift",
   "name": "Rift",
+  "version": "1.0.3-SNAPSHOT",
   "authors": [
     "Runemoro"
   ],