diff --git a/common/src/main/java/net/neoforged/gradle/common/runs/ide/IdeRunIntegrationManager.java b/common/src/main/java/net/neoforged/gradle/common/runs/ide/IdeRunIntegrationManager.java
index b4120b0c6..b5ca74f31 100644
--- a/common/src/main/java/net/neoforged/gradle/common/runs/ide/IdeRunIntegrationManager.java
+++ b/common/src/main/java/net/neoforged/gradle/common/runs/ide/IdeRunIntegrationManager.java
@@ -39,6 +39,7 @@
 import java.util.Map;
 import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * A simple manager which configures runs based on the IDE it is attached to.
@@ -123,10 +124,6 @@ public void idea(Project project, IdeaModel idea, ProjectSettings ideaExtension)
             
         }
 
-        private static String quoteAndJoin(List<String> args) {
-            return args.stream().map(arg -> "\"" + arg + "\"").collect(Collectors.joining(" "));
-        }
-
         @Override
         public void eclipse(Project project, EclipseModel eclipse) {
             ProjectUtils.afterEvaluate(project, () -> {
@@ -147,11 +144,8 @@ public void eclipse(Project project, EclipseModel eclipse) {
                         final JavaApplicationLaunchConfig debugRun =
                                 JavaApplicationLaunchConfig.builder(eclipse.getProject().getName())
                                         .workingDirectory(runImpl.getWorkingDirectory().get().getAsFile().getAbsolutePath())
-                                        .vmArgs(runImpl.realiseJvmArguments().toArray(new String[0]))
-                                        .args(runImpl.getProgramArguments().get()
-                                                      .stream()
-                                                      .map(arg -> "\"" + arg + "\"")
-                                                      .toArray(String[]::new))
+                                        .vmArgs(quoteStream(runImpl.realiseJvmArguments()).toArray(String[]::new))
+                                        .args(quoteStream(runImpl.getProgramArguments().get()).toArray(String[]::new))
                                         .envVar(adaptEnvironment(runImpl, RunsUtil::buildRunWithEclipseModClasses))
                                         .useArgumentsFile()
                                         .build(runImpl.getMainClass().get());
@@ -179,6 +173,25 @@ public void eclipse(Project project, EclipseModel eclipse) {
             });
         }
 
+        private static String quoteAndJoin(List<String> args) {
+            return quoteStream(args).collect(Collectors.joining(" "));
+        }
+
+        private static Stream<String> quoteStream(List<String> args) {
+            return args.stream().map(RunsImportAction::quote);
+        }
+
+        /**
+         * This expects users to escape quotes in their system arguments on their own, which matches
+         * Gradles own behavior when used in JavaExec.
+         */
+        private static String quote(String arg) {
+            if (!arg.contains(" ")) {
+                return arg;
+            }
+            return "\"" + arg + "\"";
+        }
+
         private TaskProvider<?> createIdeBeforeRunTask(Project project, String name, Run run, RunImpl runImpl) {
             final TaskProvider<?> ideBeforeRunTask = project.getTasks().register(CommonRuntimeUtils.buildTaskName("ideBeforeRun", name), task -> {
                 for (SourceSet sourceSet : run.getModSources().get()) {
diff --git a/common/src/main/java/net/neoforged/gradle/common/runs/run/RunImpl.java b/common/src/main/java/net/neoforged/gradle/common/runs/run/RunImpl.java
index 899ec898b..bf4ed14bf 100644
--- a/common/src/main/java/net/neoforged/gradle/common/runs/run/RunImpl.java
+++ b/common/src/main/java/net/neoforged/gradle/common/runs/run/RunImpl.java
@@ -173,9 +173,14 @@ public void configureInternally(final @NotNull RunType spec) {
     public List<String> realiseJvmArguments() {
         final List<String> args = new ArrayList<>(getJvmArguments().get());
 
-        getSystemProperties().get().forEach((key, value) -> {
-            args.add(String.format("-D%s=\"%s\"", key, value));
-        });
+        // This mirrors the logic found in Gradle itself, which also does not quote key nor value
+        for (Map.Entry<String, String> entry : getSystemProperties().get().entrySet()) {
+            if (entry.getValue() != null && !entry.getValue().isEmpty()) {
+                args.add("-D" + entry.getKey() + "=" + entry.getValue());
+            } else {
+                args.add("-D" + entry.getKey());
+            }
+        }
 
         return args;
     }