diff --git a/src/main/java/org/openjdk/jextract/JextractTool.java b/src/main/java/org/openjdk/jextract/JextractTool.java
index 4f3c92a0..4e41e922 100644
--- a/src/main/java/org/openjdk/jextract/JextractTool.java
+++ b/src/main/java/org/openjdk/jextract/JextractTool.java
@@ -484,6 +484,12 @@ private int run(String[] args) {
 
         builder.addClangArg("-I" + System.getProperty("user.dir"));
 
+        // 64 bit mode on AIX
+        if (System.getProperty("os.name").toLowerCase().contains("aix")) {
+            builder.addClangArg("-m64");
+            builder.addClangArg("-DAIX_NATURAL_ALIGN=1");
+        }
+
         if (optionSet.nonOptionArguments().isEmpty()) {
             printOptionError(logger.format("expected.atleast.one.header"));
             return OPTION_ERROR;
diff --git a/src/main/java/org/openjdk/jextract/impl/ClassSourceBuilder.java b/src/main/java/org/openjdk/jextract/impl/ClassSourceBuilder.java
index 7c1ae3a7..cfd6e9fa 100644
--- a/src/main/java/org/openjdk/jextract/impl/ClassSourceBuilder.java
+++ b/src/main/java/org/openjdk/jextract/impl/ClassSourceBuilder.java
@@ -259,7 +259,7 @@ private String primitiveLayoutString(Primitive primitiveType, long align) {
             case Long -> alignIfNeeded(runtimeHelperName() + ".C_LONG", TypeImpl.IS_WINDOWS ? 4 : 8, align);
             case LongLong -> alignIfNeeded(runtimeHelperName() + ".C_LONG_LONG", 8, align);
             case Float -> alignIfNeeded(runtimeHelperName() + ".C_FLOAT", 4, align);
-            case Double -> alignIfNeeded(runtimeHelperName() + ".C_DOUBLE", 8, align);
+            case Double -> alignIfNeeded(runtimeHelperName() + ".C_DOUBLE", TypeImpl.IS_AIX ? 4 : 8, align);
             case LongDouble -> TypeImpl.IS_WINDOWS ?
                     alignIfNeeded(runtimeHelperName() + ".C_LONG_DOUBLE", 8, align) :
                     paddingLayoutString(8, 0);
diff --git a/src/main/java/org/openjdk/jextract/impl/TypeImpl.java b/src/main/java/org/openjdk/jextract/impl/TypeImpl.java
index 24184f57..cdef2245 100644
--- a/src/main/java/org/openjdk/jextract/impl/TypeImpl.java
+++ b/src/main/java/org/openjdk/jextract/impl/TypeImpl.java
@@ -43,6 +43,7 @@
 public abstract class TypeImpl implements Type {
 
     public static final boolean IS_WINDOWS = System.getProperty("os.name").startsWith("Windows");
+    public static final boolean IS_AIX = System.getProperty("os.name").startsWith("AIX");
 
     @Override
     public boolean isErroneous() {
diff --git a/test/jtreg/generator/testStruct/struct.h b/test/jtreg/generator/testStruct/struct.h
index 07cbd7da..9c4e3124 100644
--- a/test/jtreg/generator/testStruct/struct.h
+++ b/test/jtreg/generator/testStruct/struct.h
@@ -31,6 +31,10 @@ extern "C" {
 #define EXPORT
 #endif
 
+#ifdef AIX_NATURAL_ALIGN
+#pragma align(natural)
+#endif
+
 typedef struct Point {
     int x;
     int y;
diff --git a/test/lib/testlib/JextractToolRunner.java b/test/lib/testlib/JextractToolRunner.java
index d6dc9336..170f577e 100644
--- a/test/lib/testlib/JextractToolRunner.java
+++ b/test/lib/testlib/JextractToolRunner.java
@@ -56,6 +56,7 @@ public class JextractToolRunner {
     public static final boolean IS_WINDOWS = System.getProperty("os.name").startsWith("Windows");
     public static final boolean IS_LINUX = System.getProperty("os.name").equals("Linux");
     public static final boolean IS_AARCH64 = System.getProperty("os.arch").equals("aarch64");
+    public static final boolean IS_AIX = System.getProperty("os.name").equals("AIX");
 
     public static final ValueLayout.OfBoolean C_BOOL = ValueLayout.JAVA_BOOLEAN;
     public static final ValueLayout.OfByte C_CHAR = ValueLayout.JAVA_BYTE;
diff --git a/test/testng/org/openjdk/jextract/test/toolprovider/examples.h b/test/testng/org/openjdk/jextract/test/toolprovider/examples.h
index 8fcb1706..fcffd421 100644
--- a/test/testng/org/openjdk/jextract/test/toolprovider/examples.h
+++ b/test/testng/org/openjdk/jextract/test/toolprovider/examples.h
@@ -27,6 +27,10 @@
 #define EXPORT
 #endif
 
+#ifdef AIX_NATURAL_ALIGN
+#pragma align(natural)
+#endif
+
 #define macro_byte (char) 1
 #define macro_short (short) 1
 #define macro_int 1
@@ -79,4 +83,4 @@ enum {
     enum_anon_0,
     enum_anon_1,
     enum_anon_2,
-};
\ No newline at end of file
+};
diff --git a/test/testng/org/openjdk/jextract/test/toolprovider/nestedAnonOffset/TestNestedAnonOffset.java b/test/testng/org/openjdk/jextract/test/toolprovider/nestedAnonOffset/TestNestedAnonOffset.java
index 2fe582cf..e9ff5110 100644
--- a/test/testng/org/openjdk/jextract/test/toolprovider/nestedAnonOffset/TestNestedAnonOffset.java
+++ b/test/testng/org/openjdk/jextract/test/toolprovider/nestedAnonOffset/TestNestedAnonOffset.java
@@ -91,7 +91,7 @@ public void testBaz() {
         StructLayout layout = (StructLayout) findLayout(baz);
         assertEquals(layout.memberLayouts().get(0), C_CHAR.withName("c"));
         // Note here: on some platforms, the bitfield needs to be aligned and requires more padding
-        int paddingBytes = (IS_WINDOWS || (IS_LINUX && IS_AARCH64)) ? 11 : 8;
+        int paddingBytes = (IS_WINDOWS || (IS_LINUX && IS_AARCH64) || IS_AIX) ? 11 : 8;
         assertEquals(layout.memberLayouts().get(1), MemoryLayout.paddingLayout(paddingBytes));
     }