diff --git a/Cargo.lock b/Cargo.lock
index 3a8362362e..ed0eeb7211 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1905,6 +1905,15 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "shellexpand"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a2b22262a9aaf9464d356f656fea420634f78c881c5eebd5ef5e66d8b9bc603"
+dependencies = [
+ "dirs",
+]
+
 [[package]]
 name = "smallvec"
 version = "1.4.1"
@@ -2700,6 +2709,7 @@ dependencies = [
  "heck",
  "proc-macro2",
  "quote",
+ "shellexpand",
  "syn",
  "witx",
 ]
diff --git a/crates/wasi-common/src/wasi.rs b/crates/wasi-common/src/wasi.rs
index f35055ffa8..f8b4aab780 100644
--- a/crates/wasi-common/src/wasi.rs
+++ b/crates/wasi-common/src/wasi.rs
@@ -4,7 +4,7 @@
 use crate::WasiCtx;
 
 wiggle::from_witx!({
-    witx: ["WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
+    witx: ["$WASI_ROOT/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wasi/src/lib.rs b/crates/wasi/src/lib.rs
index bd12def83a..1e812ba033 100644
--- a/crates/wasi/src/lib.rs
+++ b/crates/wasi/src/lib.rs
@@ -9,8 +9,9 @@ pub use wasi_common::{WasiCtx, WasiCtxBuilder};
 wasmtime_wiggle::wasmtime_integration!({
     // The wiggle code to integrate with lives here:
     target: wasi_common::wasi,
-    // This must be the same witx document as used above:
-    witx: ["phases/snapshot/witx/wasi_snapshot_preview1.witx"],
+    // This must be the same witx document as used above. This should be ensured by
+    // the `WASI_ROOT` env variable, which is set in wasi-common's `build.rs`.
+    witx: ["$WASI_ROOT/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
     // This must be the same ctx type as used for the target:
     ctx: WasiCtx,
     // This macro will emit a struct to represent the instance,
diff --git a/crates/wiggle/generate/Cargo.toml b/crates/wiggle/generate/Cargo.toml
index 632b649153..732fa34991 100644
--- a/crates/wiggle/generate/Cargo.toml
+++ b/crates/wiggle/generate/Cargo.toml
@@ -20,6 +20,7 @@ proc-macro2 = "1.0"
 heck = "0.3"
 anyhow = "1"
 syn = { version = "1.0", features = ["full"] }
+shellexpand = "2.0"
 
 [badges]
 maintenance = { status = "actively-developed" }
diff --git a/crates/wiggle/generate/src/config.rs b/crates/wiggle/generate/src/config.rs
index 22ff88aa24..520532a3ec 100644
--- a/crates/wiggle/generate/src/config.rs
+++ b/crates/wiggle/generate/src/config.rs
@@ -1,10 +1,6 @@
 use {
     proc_macro2::Span,
-    std::{
-        collections::HashMap,
-        iter::FromIterator,
-        path::{Path, PathBuf},
-    },
+    std::{collections::HashMap, iter::FromIterator, path::PathBuf},
     syn::{
         braced, bracketed,
         parse::{Parse, ParseStream},
@@ -143,19 +139,6 @@ impl WitxConf {
             Self::Literal(doc) => witx::parse(doc.as_ref()).expect("parsing witx"),
         }
     }
-
-    /// If using the [`Paths`][paths] syntax, make all paths relative to a root directory.
-    ///
-    /// [paths]: enum.WitxConf.html#variant.Paths
-    pub fn make_paths_relative_to<P: AsRef<Path>>(&mut self, root: P) {
-        if let Self::Paths(paths) = self {
-            paths.as_mut().iter_mut().for_each(|p| {
-                if !p.is_absolute() {
-                    *p = PathBuf::from(root.as_ref()).join(p.clone());
-                }
-            });
-        }
-    }
 }
 
 /// A collection of paths, pointing to witx documents.
@@ -201,10 +184,19 @@ impl Parse for Paths {
         let content;
         let _ = bracketed!(content in input);
         let path_lits: Punctuated<LitStr, Token![,]> = content.parse_terminated(Parse::parse)?;
-        Ok(path_lits
+
+        let expanded_paths = path_lits
             .iter()
-            .map(|lit| PathBuf::from(lit.value()))
-            .collect())
+            .map(|lit| {
+                PathBuf::from(
+                    shellexpand::env(&lit.value())
+                        .expect("shell expansion")
+                        .as_ref(),
+                )
+            })
+            .collect::<Vec<PathBuf>>();
+
+        Ok(Paths(expanded_paths))
     }
 }
 
diff --git a/crates/wiggle/macro/src/lib.rs b/crates/wiggle/macro/src/lib.rs
index ed4a3dc6f0..48f0367312 100644
--- a/crates/wiggle/macro/src/lib.rs
+++ b/crates/wiggle/macro/src/lib.rs
@@ -90,10 +90,7 @@ use syn::parse_macro_input;
 /// ```
 #[proc_macro]
 pub fn from_witx(args: TokenStream) -> TokenStream {
-    let mut config = parse_macro_input!(args as wiggle_generate::Config);
-    config.witx.make_paths_relative_to(
-        std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR env var"),
-    );
+    let config = parse_macro_input!(args as wiggle_generate::Config);
 
     let doc = config.load_document();
     let names = wiggle_generate::Names::new(&config.ctx.name, quote!(wiggle));
diff --git a/crates/wiggle/tests/arrays.rs b/crates/wiggle/tests/arrays.rs
index 9142e9f01e..9bfad46e7b 100644
--- a/crates/wiggle/tests/arrays.rs
+++ b/crates/wiggle/tests/arrays.rs
@@ -3,7 +3,7 @@ use wiggle::{GuestMemory, GuestPtr};
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/arrays.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/arrays.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/atoms.rs b/crates/wiggle/tests/atoms.rs
index 5407828fa9..b83468678b 100644
--- a/crates/wiggle/tests/atoms.rs
+++ b/crates/wiggle/tests/atoms.rs
@@ -3,7 +3,7 @@ use wiggle::GuestMemory;
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/atoms.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/atoms.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/flags.rs b/crates/wiggle/tests/flags.rs
index fcb07e7a7d..bca0a27bae 100644
--- a/crates/wiggle/tests/flags.rs
+++ b/crates/wiggle/tests/flags.rs
@@ -4,7 +4,7 @@ use wiggle::{GuestMemory, GuestPtr};
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/flags.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/flags.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/handles.rs b/crates/wiggle/tests/handles.rs
index 93e3b54d18..cb441a910c 100644
--- a/crates/wiggle/tests/handles.rs
+++ b/crates/wiggle/tests/handles.rs
@@ -5,7 +5,7 @@ use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 const FD_VAL: u32 = 123;
 
 wiggle::from_witx!({
-    witx: ["tests/handles.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/handles.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/ints.rs b/crates/wiggle/tests/ints.rs
index 36d7933e62..a3d15c79d8 100644
--- a/crates/wiggle/tests/ints.rs
+++ b/crates/wiggle/tests/ints.rs
@@ -4,7 +4,7 @@ use wiggle::GuestMemory;
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/ints.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/ints.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/keywords.rs b/crates/wiggle/tests/keywords.rs
index ea002fcc6d..bc1ee4edce 100644
--- a/crates/wiggle/tests/keywords.rs
+++ b/crates/wiggle/tests/keywords.rs
@@ -58,7 +58,7 @@ mod struct_test {
 /// Test that a union variant that conflicts with a Rust keyword can be compiled properly.
 mod union_test {
     wiggle::from_witx!({
-        witx: ["tests/keywords_union.witx"],
+        witx: ["$CARGO_MANIFEST_DIR/tests/keywords_union.witx"],
         ctx: DummyCtx,
     });
 }
diff --git a/crates/wiggle/tests/pointers.rs b/crates/wiggle/tests/pointers.rs
index c39988d115..28ef3d107d 100644
--- a/crates/wiggle/tests/pointers.rs
+++ b/crates/wiggle/tests/pointers.rs
@@ -3,7 +3,7 @@ use wiggle::{GuestMemory, GuestPtr};
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/pointers.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/pointers.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/strings.rs b/crates/wiggle/tests/strings.rs
index 3546fd1276..e68a569ed6 100644
--- a/crates/wiggle/tests/strings.rs
+++ b/crates/wiggle/tests/strings.rs
@@ -3,7 +3,7 @@ use wiggle::{GuestMemory, GuestPtr};
 use wiggle_test::{impl_errno, HostMemory, MemArea, MemAreas, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/strings.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/strings.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/structs.rs b/crates/wiggle/tests/structs.rs
index f342d4487a..ad2e43a2db 100644
--- a/crates/wiggle/tests/structs.rs
+++ b/crates/wiggle/tests/structs.rs
@@ -3,7 +3,7 @@ use wiggle::{GuestMemory, GuestPtr};
 use wiggle_test::{impl_errno, HostMemory, MemArea, MemAreas, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/structs.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/structs.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/union.rs b/crates/wiggle/tests/union.rs
index ab3dada99c..9763e488dd 100644
--- a/crates/wiggle/tests/union.rs
+++ b/crates/wiggle/tests/union.rs
@@ -3,7 +3,7 @@ use wiggle::{GuestMemory, GuestType};
 use wiggle_test::{impl_errno, HostMemory, MemArea, WasiCtx};
 
 wiggle::from_witx!({
-    witx: ["tests/union.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/union.witx"],
     ctx: WasiCtx,
 });
 
diff --git a/crates/wiggle/tests/wasi.rs b/crates/wiggle/tests/wasi.rs
index 8847959aa2..07b56db62a 100644
--- a/crates/wiggle/tests/wasi.rs
+++ b/crates/wiggle/tests/wasi.rs
@@ -7,7 +7,7 @@ use wiggle_test::WasiCtx;
 // witx is exposed with the type signatures that we expect.
 
 wiggle::from_witx!({
-    witx: ["tests/wasi.witx"],
+    witx: ["$CARGO_MANIFEST_DIR/tests/wasi.witx"],
     ctx: WasiCtx,
 });
 
@@ -16,7 +16,10 @@ wiggle::from_witx!({
 #[test]
 fn document_equivalent() {
     let macro_doc = metadata::document();
-    let disk_doc = witx::load(&["tests/wasi.witx"]).expect("load wasi.witx from disk");
+    let mut path = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    path.push("tests");
+    path.push("wasi.witx");
+    let disk_doc = witx::load(&[path]).expect("load wasi.witx from disk");
 
     assert_eq!(macro_doc, disk_doc);
 }
diff --git a/crates/wiggle/wasmtime/macro/src/lib.rs b/crates/wiggle/wasmtime/macro/src/lib.rs
index ff1df0898c..4ba1c1b9fb 100644
--- a/crates/wiggle/wasmtime/macro/src/lib.rs
+++ b/crates/wiggle/wasmtime/macro/src/lib.rs
@@ -47,10 +47,7 @@ use config::{MissingMemoryConf, ModuleConf, TargetConf};
 ///
 #[proc_macro]
 pub fn wasmtime_integration(args: TokenStream) -> TokenStream {
-    let mut config = parse_macro_input!(args as config::Config);
-    config
-        .witx
-        .make_paths_relative_to(std::env::var("WASI_ROOT").expect("WASI_ROOT env var"));
+    let config = parse_macro_input!(args as config::Config);
     let doc = config.load_document();
     let names = Names::new(&config.ctx.name, quote!(wasmtime_wiggle));