diff --git a/src/Magnum/Magnum.h b/src/Magnum/Magnum.h
index 4e1dde2b7..3da95c146 100644
--- a/src/Magnum/Magnum.h
+++ b/src/Magnum/Magnum.h
@@ -167,11 +167,21 @@ typedef std::uint32_t UnsignedInt;
 /** @brief Signed int (32bit) */
 typedef std::int32_t Int;
 
-/** @brief Unsigned long (64bit) */
+#ifndef MAGNUM_TARGET_WEBGL
+/**
+@brief Unsigned long (64bit)
+
+@attention 64-bit integers are not available in @ref MAGNUM_TARGET_WEBGL "WebGL".
+*/
 typedef std::uint64_t UnsignedLong;
 
-/** @brief Signed long (64bit) */
+/**
+@brief Signed long (64bit)
+
+@attention 64-bit integers are not available in @ref MAGNUM_TARGET_WEBGL "WebGL".
+*/
 typedef std::int64_t Long;
+#endif
 
 /** @brief Float (32bit) */
 typedef float Float;
diff --git a/src/Magnum/Math/TypeTraits.h b/src/Magnum/Math/TypeTraits.h
index e8f515b88..6d2a4c0c0 100644
--- a/src/Magnum/Math/TypeTraits.h
+++ b/src/Magnum/Math/TypeTraits.h
@@ -144,6 +144,7 @@ template<> struct TypeTraits<Int>: Implementation::TypeTraitsIntegral<Int> {
     typedef Double FloatingPointType;
     #endif
 };
+#ifndef MAGNUM_TARGET_WEBGL
 template<> struct TypeTraits<UnsignedLong>: Implementation::TypeTraitsIntegral<UnsignedLong> {
     #ifndef MAGNUM_TARGET_GLES
     typedef long double FloatingPointType;
@@ -154,6 +155,7 @@ template<> struct TypeTraits<Long>: Implementation::TypeTraitsIntegral<Long> {
     typedef long double FloatingPointType;
     #endif
 };
+#endif
 
 /* Floating-point scalar types */
 namespace Implementation {
diff --git a/src/Magnum/Query.cpp b/src/Magnum/Query.cpp
index 649994cf8..d6bee60f2 100644
--- a/src/Magnum/Query.cpp
+++ b/src/Magnum/Query.cpp
@@ -123,6 +123,7 @@ template<> Int AbstractQuery::result<Int>() {
     return result;
 }
 
+#ifndef MAGNUM_TARGET_WEBGL
 template<> UnsignedLong AbstractQuery::result<UnsignedLong>() {
     CORRADE_ASSERT(!target, "AbstractQuery::result(): the query is currently running", {});
 
@@ -151,6 +152,7 @@ template<> Long AbstractQuery::result<Long>() {
     return result;
 }
 #endif
+#endif
 
 void AbstractQuery::begin(GLenum target) {
     CORRADE_ASSERT(!this->target, "AbstractQuery::begin(): the query is already running", );
diff --git a/src/Magnum/Query.h b/src/Magnum/Query.h
index db978053f..726d508ea 100644
--- a/src/Magnum/Query.h
+++ b/src/Magnum/Query.h
@@ -107,6 +107,8 @@ class MAGNUM_EXPORT AbstractQuery: public AbstractObject {
          * @requires_es_extension %Extension @es_extension{EXT,disjoint_timer_query}
          *      for result types @ref Magnum::Int "Int", @ref Magnum::UnsignedLong "UnsignedLong"
          *      @ref Magnum::Long "Long".
+         * @attention @ref Magnum::UnsignedLong "UnsignedLong" and @ref Magnum::Long "Long"
+         *      result type is not available in @ref MAGNUM_TARGET_WEBGL "WebGL".
          */
         template<class T> T result();
 
@@ -147,9 +149,11 @@ class MAGNUM_EXPORT AbstractQuery: public AbstractObject {
 template<> bool MAGNUM_EXPORT AbstractQuery::result<bool>();
 template<> UnsignedInt MAGNUM_EXPORT AbstractQuery::result<UnsignedInt>();
 template<> Int MAGNUM_EXPORT AbstractQuery::result<Int>();
+#ifndef MAGNUM_TARGET_WEBGL
 template<> UnsignedLong MAGNUM_EXPORT AbstractQuery::result<UnsignedLong>();
 template<> Long MAGNUM_EXPORT AbstractQuery::result<Long>();
 #endif
+#endif
 
 #ifndef MAGNUM_TARGET_GLES2
 /**
diff --git a/src/Magnum/Types.h b/src/Magnum/Types.h
index 8a2be413e..ef3de0a72 100644
--- a/src/Magnum/Types.h
+++ b/src/Magnum/Types.h
@@ -42,8 +42,10 @@ typedef std::uint16_t UnsignedShort;
 typedef std::int16_t Short;
 typedef std::uint32_t UnsignedInt;
 typedef std::int32_t Int;
+#ifndef MAGNUM_TARGET_WEBGL
 typedef std::uint64_t UnsignedLong;
 typedef std::int64_t Long;
+#endif
 
 /** @todo C++14: use std::float32_t and std::float_64t [N3626](http://open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3626.pdf) */
 typedef float Float;