diff --git a/BUILD.gn b/BUILD.gn
index 0581fde..42f2093 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -46,6 +46,11 @@
   }
 }
 
+config("pdfium_implementation_config") {
+  defines = [ "FPDF_IMPLEMENTATION" ]
+  visibility = [ ":pdfium_public_headers" ]
+}
+
 config("pdfium_public_config") {
   defines = []
 
@@ -101,7 +106,7 @@
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 }
 
-jumbo_source_set("pdfium_public_headers") {
+jumbo_source_set("pdfium_public_headers_impl") {
   sources = [
     "public/cpp/fpdf_deleters.h",
     "public/cpp/fpdf_scopers.h",
@@ -125,16 +130,24 @@
     "public/fpdf_transformpage.h",
     "public/fpdfview.h",
   ]
+}
 
-  public_configs = [ ":pdfium_public_config" ]
+group("pdfium_public_headers") {
+  public_deps = [
+    ":pdfium_public_headers_impl",
+  ]
+  public_configs = [
+    ":pdfium_public_config",
+    ":pdfium_implementation_config",
+  ]
 }
 
 jumbo_component("pdfium") {
   libs = []
   configs += [ ":pdfium_core_config" ]
+  public_configs = [ ":pdfium_public_config" ]
 
   deps = [
-    ":pdfium_public_headers",
     "constants",
     "core/fpdfapi",
     "core/fpdfapi/page",
@@ -151,7 +164,7 @@
   ]
 
   public_deps = [
-    ":pdfium_public_headers",
+    ":pdfium_public_headers_impl",
     "core/fxcrt",
   ]
 
@@ -288,11 +301,11 @@
     "testing/embedder_test_main.cpp",
   ]
   deps = [
-    ":pdfium",
     "core/fpdfapi/edit:embeddertests",
     "core/fpdfapi/parser:embeddertests",
     "core/fpdfapi/render:embeddertests",
     "core/fxcodec:embeddertests",
+    "core/fxcrt",
     "core/fxge:embeddertests",
     "fpdfsdk:embeddertests",
     "fpdfsdk/pwl:embeddertests",
diff --git a/core/fxcrt/BUILD.gn b/core/fxcrt/BUILD.gn
index 3ccf31b..e4b1154 100644
--- a/core/fxcrt/BUILD.gn
+++ b/core/fxcrt/BUILD.gn
@@ -88,7 +88,7 @@
     "../../fpdfsdk/*",
     "../../fxbarcode:*",
     "../../fxjs:*",
-    "../../testing:test_support",
+    "../../testing:*",
     "../../testing/fuzzers/*",
     "../../third_party:fx_agg",
     "../../third_party:fx_lcms2",
diff --git a/fpdfsdk/BUILD.gn b/fpdfsdk/BUILD.gn
index fcea031..0194ee5 100644
--- a/fpdfsdk/BUILD.gn
+++ b/fpdfsdk/BUILD.gn
@@ -70,8 +70,6 @@
     "ipdfsdk_pauseadapter.h",
   ]
 
-  defines = [ "FPDF_IMPLEMENTATION" ]
-
   configs += [ "../:pdfium_core_config" ]
   deps = [
     "../:pdfium_public_headers",
diff --git a/testing/BUILD.gn b/testing/BUILD.gn
index 1f31d74..d2a0411 100644
--- a/testing/BUILD.gn
+++ b/testing/BUILD.gn
@@ -31,8 +31,9 @@
     "resources/",
   ]
   deps = [
-    "../:pdfium",
+    "../:pdfium_public_headers",
     "../core/fdrm",
+    "../core/fxcrt",
     "image_diff",
   ]
   configs += [ "../:pdfium_core_config" ]
@@ -88,8 +89,10 @@
 
   deps = [
     ":test_support",
-    "../:pdfium",
+    "../:pdfium_public_headers",
     "../core/fdrm",
+    "../core/fxcrt",
+    "../third_party:pdfium_base",
     "//testing/gmock",
     "//testing/gtest",
   ]
diff --git a/testing/fuzzers/BUILD.gn b/testing/fuzzers/BUILD.gn
index 038d2ce..60623c3 100644
--- a/testing/fuzzers/BUILD.gn
+++ b/testing/fuzzers/BUILD.gn
@@ -15,9 +15,7 @@
   include_dirs = [ "../.." ]
 }
 
-# "pdfium_fuzzer"s (which may depend on PDFium internals) should be added to
-# |fuzzer_list|.  "pdfium_public_fuzzer"s (which can only depend on PDFium's
-# public API) should be added to |public_fuzzer_list|.
+# All possible "pdfium_fuzzer"s.
 fuzzer_list = [
   "pdf_cmap_fuzzer",
   "pdf_codec_a85_fuzzer",
@@ -31,8 +29,8 @@
   "pdf_psengine_fuzzer",
   "pdf_streamparser_fuzzer",
   "pdf_xml_fuzzer",
+  "pdfium_fuzzer",
 ]
-public_fuzzer_list = [ "pdfium_fuzzer" ]
 if (pdf_enable_v8) {
   fuzzer_list += [
     "pdf_cjs_util_fuzzer",
@@ -46,10 +44,8 @@
       "pdf_codec_jpeg_fuzzer",
       "pdf_css_fuzzer",
       "pdf_fm2js_fuzzer",
-      "pdf_formcalc_fuzzer",
-    ]
-    public_fuzzer_list += [
       "pdf_formcalc_context_fuzzer",
+      "pdf_formcalc_fuzzer",
       "pdfium_xfa_fuzzer",
     ]
     if (pdf_enable_xfa_bmp) {
@@ -73,11 +69,41 @@
 group("fuzzers") {
   testonly = true
   deps = []
-  foreach(fuzzer, fuzzer_list + public_fuzzer_list) {
+  foreach(fuzzer, fuzzer_list) {
     deps += [ ":${fuzzer}_src" ]
   }
 }
 
+jumbo_source_set("fuzzer_init") {
+  testonly = true
+  sources = [
+    "pdf_fuzzer_init.cc",
+  ]
+  include_dirs = [ "../.." ]
+  deps = [
+    "../../:pdfium_public_headers",
+  ]
+}
+
+jumbo_source_set("fuzzer_init_public") {
+  testonly = true
+  sources = [
+    "pdf_fuzzer_init_public.cc",
+  ]
+  include_dirs = [ "../.." ]
+  deps = [
+    "../../:pdfium_public_headers",
+  ]
+  if (pdf_enable_v8) {
+    configs += [ "//v8:external_startup_data" ]
+    deps += [
+      "../:test_support",
+      "//v8",
+      "//v8:v8_libplatform",
+    ]
+  }
+}
+
 if (is_component_build) {
   group("fuzzer_impls") {
     deps = []
@@ -87,53 +113,40 @@
   }
 }
 
-jumbo_source_set("utils") {
+jumbo_source_set("fuzzer_helper") {
+  testonly = !is_component_build
+  sources = [
+    "pdfium_fuzzer_helper.cc",
+    "pdfium_fuzzer_helper.h",
+  ]
+  configs += [ ":fuzzer_config" ]
+  deps = [
+    "../../:pdfium_public_headers",
+    "../../third_party:pdfium_base",
+  ]
+}
+
+jumbo_source_set("fuzzer_utils") {
+  # In component builds, the pdfium target (which is not testonly) depends on
+  # the fuzzer sources, which may depend on this target, so add testonly only in
+  # non-component builds.
+  testonly = !is_component_build
   sources = [
     "pdfium_fuzzer_util.cc",
     "pdfium_fuzzer_util.h",
   ]
-
+  deps = [
+    "../../:pdfium_public_headers",
+  ]
   include_dirs = [ "../.." ]
-
-  # In component builds, the pdfium target (which is not testonly) depends on
-  # the fuzzer sources, which may depend on this target, so add testonly only in
-  # non-component builds.
-  if (!is_component_build) {
-    testonly = true
-  }
-}
-
-template("pdfium_public_fuzzer") {
-  jumbo_source_set(target_name + "_src") {
-    sources = invoker.sources + [
-                "pdfium_fuzzer_helper.cc",
-                "pdfium_fuzzer_helper.h",
-                "pdf_fuzzer_init_public.cc",
-              ]
-    deps = [
-      "../:test_support",
-      "../../:pdfium",
-    ]
-    if (defined(invoker.deps)) {
-      deps += invoker.deps
-    }
-    testonly = true
-    configs -= [ "//build/config/compiler:chromium_code" ]
-    configs += [
-      "//build/config/compiler:no_chromium_code",
-      ":fuzzer_config",
-    ]
-    if (pdf_enable_v8) {
-      configs += [ "//v8:external_startup_data" ]
-      deps += [
-        "//v8",
-        "//v8:v8_libplatform",
-      ]
-    }
-  }
 }
 
 template("pdfium_fuzzer") {
+  if (defined(invoker.public_fuzzer) && invoker.public_fuzzer) {
+    init_dep = ":fuzzer_init_public"
+  } else {
+    init_dep = ":fuzzer_init"
+  }
   if (is_component_build) {
     # In component builds, fuzzers are split into "_impl" and "_src" targets.
     # The "_impl" target exports the fuzzer implementation and gets statically
@@ -141,16 +154,17 @@
     # wrapper that imports the fuzzer from PDFium; this gets linked into the
     # real fuzzer executable.  In static builds, there's only a single "_src"
     # target that contains the implementation and statically links in PDFium.
+
     impl_name = target_name + "_impl"
     template_target_name = target_name
     jumbo_source_set("${target_name}_src") {
       testonly = true
       sources = [
         "component_fuzzer_template.cc",
-        "pdf_fuzzer_init.cc",
       ]
       deps = [
         "../../:pdfium",
+        init_dep,
       ]
       configs += [ ":fuzzer_config" ]
       defines = [ "FUZZER_IMPL=${template_target_name}" ]
@@ -169,9 +183,6 @@
       "//build/config/compiler:no_chromium_code",
       ":fuzzer_config",
     ]
-    if (pdf_enable_v8) {
-      configs += [ "//v8:external_startup_data" ]
-    }
     if (is_component_build) {
       # |export| should be consistent with FPDF_EXPORT In public/fpdfview.h.
       if (is_win) {
@@ -179,14 +190,14 @@
       } else {
         export = "__attribute__((visibility(\"default\")))"
       }
-      defines = [
-        "FPDF_IMPLEMENTATION",
-        "LLVMFuzzerTestOneInput=${export} ${template_target_name}",
-      ]
+      defines = [ "LLVMFuzzerTestOneInput=${export} ${template_target_name}" ]
+      deps += [ "../../:pdfium_public_headers" ]
     } else {
-      sources += [ "pdf_fuzzer_init.cc" ]
       testonly = true
-      deps += [ "../../:pdfium" ]
+      deps += [
+        "../../:pdfium",
+        init_dep,
+      ]
     }
   }
 }
@@ -351,11 +362,12 @@
       ]
     }
 
-    pdfium_public_fuzzer("pdf_formcalc_context_fuzzer") {
+    pdfium_fuzzer("pdf_formcalc_context_fuzzer") {
       sources = [
         "pdf_formcalc_context_fuzzer.cc",
       ]
       deps = [
+        ":fuzzer_helper",
         "../../:pdfium_public_headers",
         "../../core/fxcrt",
         "../../fpdfsdk",
@@ -363,6 +375,7 @@
         "../../fxjs",
         "../../xfa/fxfa",
       ]
+      public_fuzzer = true
     }
 
     pdfium_fuzzer("pdf_formcalc_fuzzer") {
@@ -375,13 +388,15 @@
       ]
     }
 
-    pdfium_public_fuzzer("pdfium_xfa_fuzzer") {
+    pdfium_fuzzer("pdfium_xfa_fuzzer") {
       sources = [
         "pdfium_xfa_fuzzer.cc",
       ]
       deps = [
+        ":fuzzer_helper",
         "../../:pdfium_public_headers",
       ]
+      public_fuzzer = true
     }
   }
 }
@@ -412,7 +427,7 @@
     "pdf_codec_fax_fuzzer.cc",
   ]
   deps = [
-    ":utils",
+    ":fuzzer_utils",
     "../../core/fxcodec",
   ]
 }
@@ -433,7 +448,7 @@
     "pdf_codec_jbig2_fuzzer.cc",
   ]
   deps = [
-    ":utils",
+    ":fuzzer_utils",
     "../../core/fpdfapi/parser",
     "../../core/fxcodec",
     "../../core/fxcrt",
@@ -514,8 +529,12 @@
   ]
 }
 
-pdfium_public_fuzzer("pdfium_fuzzer") {
+pdfium_fuzzer("pdfium_fuzzer") {
   sources = [
     "pdfium_fuzzer.cc",
   ]
+  deps = [
+    ":fuzzer_helper",
+  ]
+  public_fuzzer = true
 }
diff --git a/testing/fuzzers/component_fuzzer_template.cc b/testing/fuzzers/component_fuzzer_template.cc
index 7106417..89883f5 100644
--- a/testing/fuzzers/component_fuzzer_template.cc
+++ b/testing/fuzzers/component_fuzzer_template.cc
@@ -5,17 +5,14 @@
 #include <cstddef>
 #include <cstdint>
 
+#include "public/fpdfview.h"
+
 // This template is used in component builds to forward to the real fuzzers
-// which are exported from the PDFium shared library.  FUZZER_IMPL is a macro
-// defined at build time that contains the name of the real fuzzer.
+// which are exported from the PDFium shared library.
 
-#if defined(WIN32)
-#define IMPORT __declspec(dllimport)
-#else
-#define IMPORT
-#endif
-
-extern "C" IMPORT int FUZZER_IMPL(const uint8_t* data, size_t size);
+// FUZZER_IMPL is a macro defined at build time that contains the name of the
+// real fuzzer.
+extern "C" FPDF_EXPORT int FUZZER_IMPL(const uint8_t* data, size_t size);
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   return FUZZER_IMPL(data, size);